Unstable Biomass

Mimics possess the ability to store matter within their bodies, transforming biomass for efficient storage. However, living creatures inside the mimic take 6 HP of radiation damage every turn after 10 minutes of storage, regardless of ally or foe, as a passive effect. Nonliving matter may also be stored, with a limit of 1 cubic meter of space. Mimics cannot expand this space, nor do they have traditional storage methods like backpacks. Accessing stored items is done via the mimic's prehensile pseudopod(s) reaching within itself and therefore the mimic is invulnerable to stealing without its notice.

Use of this ability allows for on-the-fly inventory management!