I found one or two of these shells on the beach at Camber Sands:
It’s not a shell I’ve seen often, but thought they were called ‘Devil’s toenails’ because that’s what they look like (as far as I know!).
It’s actually an American Slipper Limpet (Crepidula fornicata) introduced into the southern UK from North East USA along with American oysters in 1887. The ‘real’ Devil’s toenails are Gryphaea, an extinct species of oyster from the Jurassic and Cretaceous periods. Fossilised Gryphaea are commonly found in the UK, particularly around Lyme Regis.
So scarce at Camber Sands these shells were abundant at Swalecliffe, swept up the beach into great drifts.
The limpets often form chains of up to ten individuals. In a group, they look like an animal’s paw, rather diabolical in the right light!