Sponges of the family Cladorhizidae have lost the canal system, choanocytes and osculum that define sponge filter feeding. In their place, the body surface is armed with microscopic hook-shaped spicules. Small swimming crustaceans that brush against a branch are held mechanically, without stinging cells or adhesive.
Digestion follows slowly. Cells migrate over the captured prey, enclosing it in a membrane, and break it down externally before absorbing the products. The harp form itself is a surface-area solution: multiple parallel vanes, each with dozens of upright branches, present a wide interception screen to the slow current near the seafloor.
This is a genuine reversal of a defining trait, and it evolved in deep water where suspended food particles are scarce and small swimming prey is relatively more available. The details remain thin, since the group is known largely from a small number of collected specimens and video observations, and prey capture has rarely been watched directly in the wild.