Today I Learned

Their skeletons are prized by beachcombers, but sand dollars look way different in their lives beneath the waves. Covered in thousands of purple spines, they have a bizarre diet that helps them exploit the turbulent waters of the sandy sea floor. Please follow us on Patreon! SUBSCRIBE to Deep Look! DEEP LOOK is a ultra-HD (4K) short video series created by KQED San Francisco and presented by PBS Digital Studios. See the unseen at the very edge of our visible world. Explore big scientific mysteries by going incredibly small. Pristine white sand dollars have long been the souvenir to commemorate a successful day at the beach. But most people who pick them up don’t realize that they’ve collected the skeleton of an animal, washed up at the end of a long life. As it turns out, scientists say there’s a lot to be said about a sand dollar’s life. That skeleton -- also known as a test -- is really a tool, a remarkable feat of engineering that allows sand dol