||Sandy or muddy areas of the seafloor that are dominated by sponges and their associated
communities, but do not create substrate such that they would be considered Reef Biota.
Hexactinellid "glass sponges" that are capable of forming reefs may be classified
as a Sponge Bed when occurring on sand or mud in densities not deemed adequate to
compose a reef. Many sponge species have developed holdfast organs that adapt them
to life in soft sediments, and can provide excellent structural habitat for other
creatures, including the many commensal organisms that typically inhabit the tissues
of living sponges.