The Sand dollars are species of flattened, burrowing sea urchins belonging to the order Clypeasteroida.
That shifting underside is made up of thousands of 'tube feet' used for mobility.
https://video.nostr.build/4dde0693f61d851e85a0ec1ec2bee88c7e44745ed6089b9aa5a8b70bdec28bf1.mp4
#sea #animals #amazing #videos #nature #rare
