I found this large sand dollar washed up on the beach. Never having seen a live one before, I was surprised to see that it was a nice lavender color and covered with fine spines and cilia, much different from the smooth white exoskeleton of a dead sand dollar. After taking these photos, we placed it in the water near where it washed up.
Shackleford Banks Carteret Co., NC 10/30/05
Close-up of the underside, showing the mouth at the center.
Another underside shot, showing the cilia (which were still moving) around an opening.