Grand Pleurobranch

Pleurobranchus grandis is a species of sidegill slug, a marine gastropod mollusc in the family Pleurobranchidae.

Other names: Tiled Pleurobranch.

The notum of this species is covered with a tile-like pattern of flattened tubercles composed of rings of smaller tubercles surrounding larger central ones. Most mature Hawaiian animals range from dark red brown to deep violet (cream and cream-spotted forms that are common elsewhere in the Indo-Pacific are rare in Hawaii). Very young animals are cream with violet-brown tipped tubercles that are less developed than in mature animals. Clusters of tubercles are separated by a network of white lines that disappear as the animal matures. Maximum size:  about 300 mm. Like Pleurobranchus forskalii, it usually carries the posterior portion of its mantle in a siphon-like fold.

Indo-West Pacific: Red Sea to the Philippines and down to Australia.

It is found at moderately exposed to exposed rocky sites at depths of 5-10 m (15-33 ft) as well as in moderately protected sand habitats at 18 m (60 ft). However, it's listed as "fairly common at depths of about 30 m (98 ft)" and has also been photographed to depths of 74 m (243 ft) by HURL submersibles. Rarely, it can be found in tide pools.