Brightgill

Brightgill mushrooms represent a captivating group of shelf fungi distinguished by their enchanting, stunningly bright bioluminescent glow. These fungi thrive exclusively on the damp walls of caves, where they derive nutrients from the deep, intertwined roots of ancient and dead trees. Their most notable feature is their large fruting bodies, referred to as conks, which have a bracket- or shelf-like morphology. The undersides of these conks are lined with delicate gill-like structures, called lamellae.   One of the remarkable traits of brightgills is their ability to grow continuously, seemingly without limits. While they typically reach impressive sizes of around 2.6 feet, some extraordinary individuals have been recorded at sizes exceeding 12 feet. The robustness of brightgills is akin to that of other shelf fungi, with a tough, resilient structure that allows them to endure their environment. The gills situated on their undersurface are responsible for spore production, with variations in size reflecting the overall dimension of each species.   Currently, there are three known species of brightgills, all native to subterranean ecosystems, where they emit a soft luminescence from their lamellae. It is theorized that their spores are dispersed into other cave systems through natural air currents and carried by small animals such as insects and bats. Some species of brightgills grow to such an extent that they can provide habitat for small bats and various other cave-dwelling creatures within their gills. Their absence on the surface is likely due to the fierce competition from other fungal species.   The Ebonhollow Expanse, an impressive and intricate cave system located beneath Arkynshire Lake, serves as the primary habitat for these extraordinary fungi. Within this subterranean labyrinth, all known species of brightgills have been discovered, with some specimens reaching record-setting sizes, making them some of the largest mushrooms on the planet.
Average Size
2.6 ft
Origin/Ancestry
Ebonhollow Expanse
Body Tint, Colouring and Marking
Common: Light grey; bright blue bioluminescence
Rime-Edged: Dark medium grey with a rusty-brown outer edge; dim blue bioluminescence
Emerald: Dirty-white; green bioluminescence
Geographic Distribution
Species
Common Cave Brightgill
Rime-Edged Brightgill
Emerald Brightgill

Geographic Distribution

All species of brightgills have been documented in caves and subterranean environments across the diverse landscapes of Azlov, thriving wherever conditions allow, except in waterlogged or fully aquatic caverns.   The most prominent known location for these intriguing fungi is the vast Ebonhollow Expanse, an enormous cavern rich in biodiversity. This expanse is home to all recognized species of brightgills, along with a myriad of other fungal organisms.   It is hypothesized that brightgills have colonized other cave systems either via air currents or by spores adhering to small animals such as insects and bats. However, they have not been observed growing on the surface and have also been found in caves far from the caverns where they were thought to originate, which renders the air currents hypothesis less credible in explaining their extensive underground dispersal. Insects are known to feed on fungi and play a crucial role in dispersing spores, while bats have frequently been observed roosting among the lamellae of large brightgills. Furthermore, the spores have been studied under microscopes and have hooked barbs on the outer surface of the spore, allowing it to stick to the fur of bats like a burr.   While unproven, there is a prevailing theory that these remarkable fungi may have originated in the Ebonhollow Expanse itself, as evidenced by the presence of some specimens that are considered the largest mushrooms ever recorded.  

Anatomy & Morphology

Brightgills exhibit a consistent structural framework and overall shape; however, they show significant differences in coloration and morphological characteristics of the gills on their undersides. Classified as shelf fungi, brightgills typically develop on the vertical surfaces of cave walls and decaying wooden logs, forming a distinctive horizontal platform reminiscent of a shelf. As with other forms of fungi, the root structure comprises of mycelia, while the mushroom is its fruiting body.   These mushrooms feature a circular, bracket-like form, with a dense core positioned at the edge attached to the supporting surface. Brightgills possess gill-like structures, termed lamellae, adorning the underside of the mushroom, rather than a honeycomb-like composition of fused, individual tubes, which are commonly found on most shelf mushrooms.  

Morphology & Bioluminenscene

Each species of brightgill presents unique characteristics in the arrangement and attachment of the lamellae, as well as variations in their luminous properties. The bioluminescence displayed by these mushrooms surpasses that of most other fungi, likely serving to attract insects and other small animals that contribute to the dispersal of their spores. The bioluminescence is visible to the naked eye, but only while the mushroom remains attached to its mycelial roots.  

Common Cave Brightgill

The Common Cave Brightgill, recognized as the largest among the species, showcases sinuate (notched) gills with spaced distances[1] that provide ideal hiding spots for bats.   Generally, the fruiting body of this species has a pale light grey coloration, closely resembling that of an oyster mushroom when viewed outside a cave. However, in underground or dark environments, it radiates a soft, ethereal light blue hue, with the gills shining the brightest. This brilliant glow effectively overshadows its base color. Conversely, if the mushroom is harvested or damaged, detaching it from its mycelium, the vibrant glow will gradually fade, revealing its true light grey color.

Rime-Edged Brightgill

The Rime-Edged Brightgill is characterized by a notched gill attachment coupled with a commonly subdistant spacing arrangement.[1] This species is medium-sized compared to the other brightgill species. Though it is the dimmest among the brightgills, its bioluminescent quality remains impressively bright overall, with the gills standing out as the most radiant part of the mushroom. The top of the mushroom, called the context[2], displays a darker grey shade, accented by a rusty-brown ring along the outer edge. Its more substantial context and darker pigmentation impede the passage of light to a greater extent than seen in other species.   Notably, some larger specimens reflect a secondary ring encircling the central portion of their context, suggesting a pattern in which these rings form at regular intervals. Thought of as a way to date the mushrooms, however, the duration of these intervals remains a mystery, though it is speculated that they span many years. Specimens that are thought to be very old have only been observed to have no more than two rings, one inner ring, and the outer edge.

Emerald Brightgill

The Emerald Brightgill stands as the smallest among the brightgill species, featuring a subdecurrent gill attachment with crowded lamellae spacing.[1] These mushrooms grow closer to the substrate, making them particularly attractive to insects. This species is considered rare and is found exclusively in a limited number of caves.   The top of the mushroom, called the context[2], displays a dirty-white coloration, while, true to its name, it is distinguished by a striking bright green glow that entices various insects, including crickets and a cave-dwelling grasshopper-like insect known as mushroomhoppers. The luminous green glow of the emerald brightgill is believed to result from its lower metabolic rate relative to other brightgill species.
 

Trivia

  • Brightgills were inspired by the classic "glowshroom" / glowing mushrooms in fantasy settings.
  • The Common Cave Brightgill was inspired by the Glowing Mushroom from Skyrim.[3]
  • References

    1. "Glossary" — on MushroomExpert.com; Retrieved December 9, 2025.
    2. "Polypore" — on Wikipedia; December 1, 2025.
    3. "Skyrim:Glowing Mushroom" — on UESP wiki; February 4, 2024.


    Cover image: by Nulcheck

    Comments

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    Dec 9, 2025 22:01 by Valentine Myers

    I'm a huge sucker for a good glowing mushroom, and I approve!

    Dec 9, 2025 22:05

    <3 They're fun!

    Fly high, Guardian. o7
    — Nulcheck
    Dec 9, 2025 23:16 by Dr Emily Vair-Turnbull

    Omigosh, the idea of bats roosting in the gills! <3 I wonder if you could curl up on top of one of the bigger ones. Might be a slightly safer space to make camp rather than on the cave floor.   Yay for glowy glowy mushrooms!

    Emy x
    Explore Etrea | WorldEmber 2025
    Dec 10, 2025 17:24

    Thank you! I had a feeling you were going to like this one <3   If you don't mind having bats a couple of feet below you, camping on top of one of the big ones probably would be safer than sleeping on the cave floor :) And it'd be like you'd have a night light, too, haha!

    Fly high, Guardian. o7
    — Nulcheck
    Dec 10, 2025 08:50 by Imagica

    I love a mushroom article! I have to ask, are they edible? Someone must have tried..

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    Dec 10, 2025 17:27

    Thanks!   I have thought of it briefly, but haven't decided yet. I'm sure someone has tried, but I'll have to think about what happened to them. Realistically speaking, I'm not sure eating a glowing mushroom is a good idea, haha.

    Fly high, Guardian. o7
    — Nulcheck
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