Goniodoris castanea is recognisable according to following characteristics :
- the body is tuberculous and brown, and it is covered in white spots
- the mantle is much shorter than the animal's foot
- the gills form a large flattened circle and they are located in the centre of the body (but near the mantle edge)
- the rhinophores are lamellate and the oral tentacles are small and flattened

Goniodoris castanea feeds on the ascidians Botryllus schlosseri, Botrylloides leachi and Ascidia mentula.

Mediterranean