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.

This is another installment of the PBS Deep Look series; this installment is adapted from the “It’s OK to be Smart” series. If no film or link appears in this email, go to the blog to view it by clicking on the blog title above. If the film stops & starts in an annoying manner, press pause (lower left double bars ||) to let it buffer and get ahead of you.   [Chuck Almdale]