[1] The pilgrim hervia is an aeolid sea slug, its average size is between 3 and 5 cm.

Those cerata act like gills, and each one contains a terminal outgrowth of the digestive gland, a diverticulum.

The head, which is the same colour as the body, has a pair of bright orange rhinophores, and with two whitish long buccal tentacles, which look like horns.

This species occurs in the Mediterranean Sea and in the eastern Atlantic Ocean from the Channel south to Senegal.

[3] This sea slug prefers to live on rocky bottoms and slopes in clear and well-oxygenated water, between 5 and 50 m in depth.