Can you help me identify this tonna ?

[tunman]

Hi Jeremy, Paul,
This is actually a Tonna allium (Dillwyn, 1817). The spots on the spiral sculpture might be misleading a bit, and it is a heavier specimen than the usual ones, with a quite elabourate lip. Nevertheless, it's easily identified by the shape and density of the spiral sculpture as well as the shape and size of the fasciole. T. allium can occur with different colouring on the ribs. Sometimes no colour at all (white), sometimes spots, and sometimes fully brown. All is related to food sources in its environment.
Should you require some photographs showing the variety of T. allium, please don't hesitate to ask.

Cheers,

Chris