Acarnidae

Acarnidae is a family of sponges belonging to the order Poecilosclerida. It has a global distribution, although several genera occur primarily in colder temperate waters, and several have very restricted ranges. It is estimated that there are several hundred species.

== Description == Species form encrusting, massive, fan-shaped or digitate (small, un-splitting branches growing from a spreading base) growth forms that may burrow into the substrate. The species of many genera produce fistules.