Sea Urchin

Sea Urchins are spiked animals living around the shores of Koholint Island. They can be passed by pushing them with the shield. It is required that Link uses his shield to move the Sea Urchin blocking the way to the sword. Link can also use the sword or Boomerang to destroy them, after obtaining them.

Trivia
The Sea Urchin is another Mario reference, seeing how it looks nearly identical to the Sea Urchins in Super Mario World.