Cerulea

The moon was subject to a recent (in cosmological terms) heavy bombardment, creating the craters that dot its surface and bringing oceans of water. Cerulea has a notoriously malleable crust and highly active mantle due to its proximity to Cell, the stretching and squeezing forces exerted by the gas giant birthing hundreds of volcanoes.

The planet has been populated with primordial marine life by the Gamics, but its atmosphere has not developed enough to support them evolving onto land. Under the waves, organisms congregate around large reef-like formations that act as a sort of hub for near-surface life. The 'reef' supports them and they support the reef, but this system leaves large swathes of the ocean uninhabited. The reefs have very deep roots that occasionally spring out near the surface, up to hundreds of meters away from the main body. Further down, life becomes decentralized, with a highly predatory ecosystem slowly evolving in the mid depths. At the deepest parts of the sea, long and thin veil-like organisms dominate, feeding on marine snow and being transported by the ocean current.

Every few dozen years, a sort of algal bloom spreads across the seas of Cerulea, choking out plant life and turning its oceans a light green, easily visible even from space. This process appears to have rapidly evolved as a sort of ecosystem 'reboot', akin to how wildfires can reset a forest and provide vital nutrients.