Nivris eggshell

When first laid, nivris eggs are soft and pliable, much like turtle eggs. As the embryo develops in the shell, it exhausts the space available and begins to press against the soft casing. At this point, the eggs are expelled from the male’s egg crypt and the process of incubating them externally begins. To protect it, the egg is coated in a mucous that hardens on contact with air.

As the embryo grows, the egg sac stretches but the mucosal layer cracks, requiring the parent to repeatedly re-coat the egg. The resulting eggshell can be up to 7mm thick and is a coveted material for construction.

Uses

Worked with a hammer and chisel or a bandsaw, and cut along its original fault lines, nivris eggshell is traditionally used for rooftiles, especially capstones. The eggshell is waterproof, fireproof, and thermally resistant. It is not damaged by lightning strikes and carrying a piece is believed to make the bearer immune to both lightning and lice.

If it can be ground into powder, it can be made into a tough, milk-coloured glaze for pottery that is resistant to heat and cold - a clay cupboard internally glazed with njvris shell has been used in lieu of refrigeration since the middle of the 6th century.

Harvesting and farming

Eggshells are most commonly harvested from nest sites in the mid-to-late summer.

Although nivris are farmed for their oil, the aggression of breeding-age females and brooding males makes them too dangerous to keep - the males only begin to produce the desired mucous once they have expelled their eggs and the amount produced is dependant on the number of eggs they incubate. All efforts at domestication and the use of dummy eggs have resulted in failure, often with widespread property damage and loss of life.

Poachers have been known to kill brooding males to access the eggshells before they crack, allowing the shells to be used whole. Although the larger piece-size is desirable, these eggs are thinner and smaller in diameter than naturally discarded eggshells.