False Fission Drum

Tentatively Polymephycite tympanum. Not animal, plant, or fungus, but a fourth category of complex life analogous to Earth protists.

Central structure

The central stipe is a biopolymer akin to chitin or keratin held upright by a beard of air-filled sacs (pneumatocysts).

Dual feeding strategy

Photosynthesis is the primary nutrient source, but cave-dwelling drums subsist on dissolved nutrients.

Reactor glow

Adults develop a large bioluminescent swelling called a sprangia. Its blue light precisely mimics the Cherenkov radiation of a nuclear fission reactor immersed in seawater.

Assessment

further investigation required. Await further updates.