Polymastiidae

Polymastiidae is a family of demosponges found in oceans throughout the world. It is the only family in the monotypic order Polymastiida. A useful diagnostic characteristic of members of this family is the presence of numerous surface papillae although this feature is shown by some other sponges.

Tylexocladus is a genus of deep-water sea sponge belonging to the family Polymastiidae. These are small rounded sponges with a bristly surface bearing one or more raised openings (known as "osculae").