These, to be honest, aren't members of the Cuspipoda, they are the sitser taxon. In difference to their relatives these animals are sessile. They prefer the shallow waters of Xibalba but a few species are also present in the endless deeps of the global ocean.
Like the Cuspipoda they have "legs" which are consists on one segment and are surrounded by muscles. They feed on plankton with an suction feeding technique. Suddenly they open their "legs" and the resulting vortex draws the microscopic prey animals.