Polymastia hirsuta

Polymastia hirsuta is a species of demosponges belonging to the family Polymastiidae. It is found in various subtidal habitats in the far north of North Island, New Zealand.

This is a usually circular sponge up to 7 cm in diameter. This rather distinctive species is generally brown and silt-covered but with prominent papillae appearing as bright yellow, silt-free lumps over the whole surface.

References

• Michelle Kelly-Borges & Patricia R. Bergquist (1997). "Revision of Southwest Pacific Polymastiidae (Porifera: Demospongiae: Hadromerida) with descriptions of new species of Polymastia Bowerbank, Tylexocladus Topsent, and Acanthopolymastia gen. nov. from New Zealand and the Norfolk Ridge, New Caledonia" (PDF). New Zealand Journal of Marine and Freshwater Research. 31 (3): 367–402. doi:10.1080/00288330.1997.9516772.