Polymastia aurantium

Polymastia aurantium is a species of demosponge belonging to the family Polymastiidae. It is found in intertidal habitats including tide pools in the vicinity of Auckland, New Zealand.

This is a thickly encrusting sponge with a soft, fleshy texture, growing in patches up to 18 cm across. The outer layer is bright orange with a yellowish-brown interior. The surface is marked with widely spaced papillae: When the sponge is in a location affected by wave action, the papillae are located on distinct lamellae running in a single direction over the whole surface of the sponge.