Have recently seen many small curved objects on the beach. They appear to be just sand - pick one up and it breaks up into nothing but sand. Therefore, I rather assume they are some sort of cast. Possibly some sort of protein binding it all together.

Each one is something like 75 mm long.

Across the beach there must be untold thousands:

https://www.dropbox.com/s/iyu0ebxod0...small.jpg?dl=0

And, close-up, moved onto a black background:

https://www.dropbox.com/s/stlif4xstw...small.jpg?dl=0

I have tried image searches - Google, TinEye, Bing. Nothing I've found so far matches!

Any good ideas about how to preserve one - as a specimen? Obviously, without changing its look. Has to be a simple technique using pretty safe materials as it would have to be done on a public beach.