When seen on the shore R. coronata usually appears black or pitchy brown with a whitish collar and a few light marks. A tuft of simple gills (1) may protrude from below the posterior of the mantle on its right side. The anus is under the rear edge of the mantle; white faeces (2) are often visible on the adjacent foot when it is grazing on calcareous Lithothamnium.

marinvert.senckenberg.science/image-browse/