This cuttlefish 'bone' - the internal shell of this common cephalopod - was washed up on Blast beach at Dawdon on the Durham coast today.
When I was a kid living in Sussex I often saw these lovely animals swimming at East Head, in a warm sandy bay in Chichester harbour where I went sailing, and I frequently found their 'bones' on the shore. We used to collect them for our pet budgerigar, as a calcium-rich dietary supplement.
I haven't seen cuttlefish 'bones' very often here on the North East coast.
The first thing that strikes you when you pick these objects up is how light they are. They function as buoyancy aids and are full of tiny air chambers. You can find some wonderful images of their microscopic internal structure on this Wikipedia site - click here.
Cuttlefish illustration from Shell Life by Edward Step (1901).Frederick Warne & Co.
Visit the ARKive web site - here - for more information about these animals and for some lovely movie clips