What were these?

[siege]

Found while rip-cleaning the sand I got...



Anyone have any idea what either sets of things are?

I'm especially interested in the things in the middle. I threw the first one or two I found to the side, thinking it was just a chip off of something, and then after I found a few more realized it was a... thing, of some sort. Almost tooth-like, but reasonably certain that's not what it is. They're about 15mm in length or so - which should give a scale for the round things.

 

[myvwrock]

Well the outside ones were definitely snails. It looks like the middles might fit together like a crab leg just a hunch

 

[siege]

Well the outside ones were definitely snails. It looks like the middles might fit together like a crab leg just a hunch

Definitely looks like a snail of some kind... but... flat??? And there's no hollow part? There were quite a few of those.

As for the other, I don't think so? These things are hard and stony, and there were more than a few, all this same size and shape.