These are brown and contain symbiotic zooxanthellae, unicellular photosynthetic algae which supply the polyp with nutrients while benefiting from its nitrogenous waste.

[3][4] Umimayanthus parasiticus is found in the Caribbean Sea, the Gulf of Mexico, Florida, Bermuda and the Bahamas at depths varying from 7.5 to 30 metres (25 to 98 ft).

It is probable that the coral benefits from the flow of water into and out of the sponge which increases the number of food particles coming within its reach.

The sponge is a filter feeder and feeds on the bacteria and dissolved organic matter it removes from the water passing through its tissues.

Some sponges produce anti-fouling compounds which they release into the surrounding water to try to prevent other organisms colonizing their surface.