Sand Dollars

I had a "Today I Learned" moment at work on Friday. We got a shipment of live sand dollars in and I didn't take a look at them until several hours later. 

Let's review: marine biology bachelor of science degree here, and an environmental science master's degree. I have only ever seen live whole sand dollars. Round. All the way round. I've seen plenty of chipped ones that are dead. I could not stop staring at the batch of sand dollars that were collected for us. They were all chipped and broken to some degree and...alive.

For all my years beach combing, collecting cool objects, and studying marine life, I had absolutely no idea this was possible. I was impressed by their hardiness - some look like chew toys. How much can they lose before their...missing parts...become an issue? Hmmmm.