Terrorpin
Terrorpin are turtle-like enemies that appear in the Dark Palace of A Link to the Past.
A Link to the Past
When Link first encounters a Terrorpin, it appears to be an indestructible enemy. Their hard shells are impenetrable by Link's Master Sword. As Link journeys through the Dark Palace, he will acquire the Magic Hammer and he can use his this weapon to flip a Terrorpin upside down. Whenever Link uses the Magic Hammer near a Terrorpin it will flip upside down, leaving its soft belly vulnerable to Link's attacks. However, this will only last for a few moments, as the Terrorpin will eventually flip back to its proper positioning.
If Link uses the Magic Hammer a second time while the Terrorpin is flipped over, the enemy will revert back to its normal position. Terrorpins move rather slowly, moving either vertically or horizontally, being unable to move diagonally. If they come into contact with Link, a full heart of damage will be done. After they are flipped on their bellies, two slashes with Link's Master Sword will do them in.