i once tried to pry a limpet shell from a shoreline rock, and discovered that the lovely crenellations around the perimeter of the shell are actually blade-sharp, and that the limpet clings to its chosen surface with almost surreal tenacity. my bloody fingertips convinced me to admire all future examples visually, but not tactilely.

limpet shell (from a marine sea snail)

north captiva island, florida gulf coast