Little hermit crab Pylopagurus discoidalis living in an old ballpoint pen. Notice how its claw is ro

Little hermit crab Pylopagurus discoidalis living in an old ballpoint pen. Notice how its claw is rounded, perfectly shaped to form a protective seal for the round pen opening. This species is normally adapted to live in scaphopod shells, which also are elongated with a circular opening. One of the rare cases where nature can make good use of our plastic waste.