The entire mushroom is covered with sand. It grows, partially buried in the sand, along the Atlantic coast and the Great Lakes coast, from late summer through the fall.
Although it's supposed to be edible (but not very good), trying to eat it can still kill you: you die of old age before you can remove all the sand!
In fact, so much sand fell off the mushroom I used as a model for the sculpture photographed above, I glued the same sand onto the sculpture to complete the piece.