This is a large mollusc and like the Sea Hare shown elsewhere on this page, has an internal shell. It is a relatively large animal and can be about 18cms long and perhaps 12cms across. They are found inshore in summer months on western coasts (sometimes in great numbers) where they prefer muddy gravel bottoms. They feed here on sea squirts and lay large and very attractive coils of eggs - see next picture.The common name Highland Dancer is starting to be used by some.
s.s.Port Napier, Skye. W. Scotland