If you are like me, you’ve picked up a sand dollar on vacation somewhere, and it looked something like this.

It probably had some nice little card attached to it that explained the supposed religious significance of the 5 points, etc. And you may or may not have broken it open to see the “doves” inside.

But, if you are like me, you had no idea that sand dollars are really sea urchins. And really, they look like this:

The nice white keepsake is what is left after a giant starfish swims over the live sand dollar, expands its stomach to envelope the creature, and then liquefies all of the live cells. The remaining white shell is actually an exoskeleton. The doves are, to simplify it greatly, kind of like teeth.

I think I liked it better in the gift shop. Sea Urchin. Ewww.

Source: Planet Earth on The Discovery Channel