Top Shells

Top shells include some of the most attractive gastropods found on Cornish shores. There are five common and several rare species found here. The common species are Flat Top Gibbula umbilicalis, Grey Top Gibbula cineraria, Giant Top Shell Gibbula magnus, Painted Top Calliostoma zizyphinum and the Thick Top Monodonta lineata.

         Flat Top Gibbula umbilicalis

           Painted Top Calliostoma zizyphinum

         Grey Top Gibbula cineraria

           Thick Top Monodonta lineata

         Giant Top Shell Gibbula magnus

Flat Top Gibbula umbilicalis

This small topshell is abundant in Cornwall.

It is a drab grey green, with purplish wavy stripes. It has an umbilicus.

Grey Top Gibbula cineraria

Very common in Cornwall, specifically on rocky beaches. It is grey (but can have a yellow tinge) with brown to purple stripes.

The umblicus is oval shaped. Live specimens can only be found with the lowest tides

Giant Top Shell Gibbula magnus

This is a species with a southern distribution, it is not common in most of the UK but can be locally so in Cornwall. To be found alive it must be looked for at the lowest tides. It can be rather large for a top shell hence its name. The shell is covered by reddish stripes. The umbilicus is large.

Painted Top Calliostoma zizyphinum

Frequent on rocky beaches particularly at the lowest tides. If the shell is found complete, it has a sharp top and a relatively flat bottom. However the majority of shells found have their top missing. Colouring varies from violet, purple to red. Local specimens of painted tops can be found with the umbilicus covered by an inner lip.

In spring the females lay gelatinous ribbons of eggs, which are then fertilised by the males. The eggs hatch producing shelled juveniles.

Thick Top Monodonta lineata

This is a species with a southern distribution which is common in Cornwall. This is a large purplish shell reaching over an inch.

Found on rocky shores, it’s thick and heavy shell can survive even the most exposed shores. There is a tooth 1 or notch on the aperture