Although seemingly ordinary-looking, this Sand Dollar did recently corner me in a coffee shop, and expound on the connections between whale song and String Theory for 45 minutes. So, I think my ID is accurate. RIP.
Hundred of them...different colors...
The term sand dollar (or sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) refers to species of extremely flattened, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are known as sea biscuits. Related animals include the sea cucumbers and starfish.