From 2speccers2tools wiki

Amidst the sudden proliferation of small fauna in 2s2tworld’s seas, it is inevitable that predators - some of which have not had a significant presence for countless generations - would experience similar bouts of diversification to exploit this ever-expanding bounty. Derived from the offspring of Mimic Legoboxes carried far from their subtropical home waters, the Mimicubes have adapted to a wide array of repertoires and have become a somewhat common occurrence in the benthos.

As slow-moving predators, Mimicube diets consist predominantly of prey that likely won’t get far. A Mimicube of a certain species will first bury itself into the substrate via rows of locomotory cirri along its margins, exposing only the lid and its twin tentacles, lending to the genus’s informal name as they mimic a variety of morsels their prey may feed upon. While Mimicubes retain the chemoreceptive setae on the upper lid, they also come equipped with a row of simple eyes inside, capable of detecting shadows and some indistinct shapes - giving it awareness of both prey and predator presence alike. The mimic tentacles also double as organs receptive to subaquatic vibrations. Mimicubes employ a few strategies for acquiring prey of certain size ranges - while smaller items blundering into a Mimicube may simply be sucked inside via the water current created by the rapid flapping of its lid, more substantial prey are grappled and neutralized by two rows of tentacles rimming the inner front margins. While the bulk of their diet consists of benthic or slower prey, speedier pelagic prey like the Ripplet may also succumb to a Mimicube’s efforts - ending up lassoed by its mimic tentacles. Once ingested, subdued prey is pulled apart by the inner tentacles, then pulled into a digestive chamber by muscular contractions; foodstuffs there are bathed in a potent mix of digestive acids and the activities of specialized Bruh Within cultures. As this is a blind gut, any waste material left over is coughed out as minute pellets. Because Mimicubes exert comparatively little activity otherwise, they have low metabolisms and can subsist off of a single sizable feeding for up to a few days - especially among larger species.

Mimicubes retain the resistance to radioactive and spiteful prey common to all legobox fauna.

Within a Mimicube’s form are a number of other anatomical innovations, many of which having developed to better support a larger, hungrier organism. Simple diffusion is no longer an efficient means of gas exchange, as gills lining the box interior now fuel a Mimicube’s body with precious oxygen; gases and nutrients alike are distributed via hemocoel. A chitinous framework gives structural integrity at the sizes these boxfauna attain. To process this variety of sensory information, a nervous network radiating from a central ganglion has developed.

Aside from burying into the substrate, a Mimicube’s cirri are also useful in slowly crawling along in search of more productive feeding spots. During particularly plentiful conditions, Mimicubes of a species expel copious gametes into the water, which then conjugate to form spores. These spores then develop into planktonic larvae, some of which grow large enough to settle onto the seabed and attain adult feeding habitats. It is due to these breeding habits that ensured the genus’s spread.

The many species of Mimicube are relatively easy to identify, given the proper materials. The shape of the mimic tentacles depends on the local assemblage of flora and similar organisms (e.g. northern species have tentacles resembling poralp trees, while southern species have turdhurb-mimicking tentacles, and twilight species’ tentacles imitate large wigglers - complete with symbiotic OBM cultures proxying their glow). Beyond their tentacles, species come in colors matching the color of the substrate. Larger species are usually more tolerant of radioactive and spiteful prey than their smaller cousins.

Due to their diversity and success as sessile predators, Mimicubes have pressured the ancestral Mimic Legoboxes close to extinction, as they simply couldn't keep up with the competition at feeding on large fauna.

Close-up anatomy of a Mimicube species.