Filtercubes

From 2speccers2tools wiki

With their larger progeny monopolizing meat-eating niches, the remaining populations of Mimic Legobox found themselves in a precarious position - any direction into specializing for carnivory was simply outdone by the Mimicubes, and these populations were pushed to the brink of extinction. However hope was not entirely lost, as these relict legoboxes instead adapted further for smaller meals. Thanks to their high spawning rates, genetic changes were able to accumulate much faster, and the odds for dispersal were bolstered; this eventually reached a point in which these Mimic Legoboxes became a genetically distinct taxon - the Filtercubes.

To make the most of their obligate planktivory, Filtercube species possess feathery cirri on their inner lid and base, straining their meals from the water column. To ensure a steady supply of food, the lid opens and shuts at quick, regular intervals; this generates a modest, yet consistent sucking flow of water. Aside from feeding, these cirri are also keen chemoreceptors. As a consequence of generations of subsisting on small fare, the Filtercubes themselves have become small to make the most out of these catches. Although no longer useful in duping prey, the twin lid tendrils still serve a crucial function in detecting underwater vibrations.

During times of plenty such as plankton blooms, Filtercubes of a species expel copious gametes into the water, which then conjugate to form spores. These spores then develop into multitudinous planktonic larvae, few of which survive to adulthood.

Filtercubes are vastly diverse and number in many dozens of species, much of which are difficult to distinguish from one another, especially as variant morphologies may have arisen more than once; trends among subgenera are easier to note however. Basal Filtercubes still bury themselves in the substrate via marginal cirri, while some more derived species utilize adhesives on the bottom box face to stick to hard rock. The greatest diversity of Filtercube species occur within temperate coasts due to the ample access to nutrients and oxygenated water there, although they’re still abundant in tropical and twilight waters. The largest such species are indeed found in twilight depths, and often supplement their diet with marine snow. All species retain some resistance to radiation and spite accumulation.