Polymastia tapetum

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

This is an encrusting sponge growing in patches up to 60 cm across. The outer layer is bright yellow or orange with a darker interior. The whole surface is thickly covered in smooth triangular papillae up to 15 mm in height. As this sponge is commonly covered in silt, the papillae are often the only part of the animal visible.

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.