I found this recently on the beach at Walton-on-the-Naze in Essex. Looks and feels like a pebble on top but on turning over, a shell (Whelk) is revealed...
It looks like it's in a fossil material of other shells (red crag). Here's a closeup
Can anyone put an age on this specimen and tell me how it was formed?
Message was edited by: Luanne
It looks like a concretion of red crag shelly sandstone that has incorporated a gastropod during its formation. Concretions are formed where an area of sediment is further cemented together by an accumulation of additional minerals, making it harder than the surrounding rock so that it erodes out of it intact.
The shell has been exposed and broken during weathering, making it difficult to identify from guides which usually show the exterior of the shell only. An expert might be able to have a go at identifying it from the general proportions and the shape of the columella (the column around which the gastropod shell coils).