#macrocrinus

alt: Macrocrinus, a crinoid (echinoderms with radial arms attached to a central cup suspended on a stalk like a flower, hence the name sea lily.) with something called an "anal chimney" (yes that's what it's called.) which is an extension on its tegmen that looks like a long tapering tube jutting out of its cup. This tube is meant as a deterrent for platyceratid snails from stealing their shit, literally, since it places their anus and undigested food further away from the base of the cup which the snails have an easier time attaching to. The snails of course, responded to this by simply drilling into the sides of these anal chimneys...