Thick Topshell

Osilinus lineatus


Lives around the low tide mark, grazing on algae and seaweeds on the rocks.

How to identify

A conical whorled shell, pale grey in colour with a maroon zig-zag pattern and mother of pearl around the mouth. Distinguished from similar, snail-like periwinkles and topshells by the 'tooth' just inside the mouth of the shell.

Where to find it

Found on rocky shores around south west England and Wales.


When to find it

  • January
  • February
  • March
  • April
  • May
  • June
  • July
  • August
  • September
  • October
  • November
  • December

How can people help

Molluscs provide a vital link in the food chain for many of our rarer species. Our seas and coastline are in need of protection if we are to keep our marine wildlife healthy. The Wildlife Trusts are working with fishermen, researchers, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. This work has recently had a massive boost with the passing of the Marine Bill, promising sustainable development of the UK's marine environment. Do your bit for our Living Seas by supporting your local Wildlife Trust.

Species information

Common name
Thick Topshell
Latin name
Osilinus lineatus
Aquatic gastropods (e.g. sea snails)
Diameter: 3cm
Conservation status