The mosaic pleurobranch has a sturdy rounded body with a bumpy skin.

The skin has occasional elongated papillae and is a glowing pinkish red.

Like all other sidegill slugs, there is a single gill on the right hand side of the body.

[1] This animal has been found off the southern African coast from the Atlantic side of the Cape Peninsula to Algoa Bay.

Its egg mass is a wavy white spiral with one edge attached.