Sea Urchin

are recurring NaN Enemies in.

In, they appear on Toronbo Shores. While they can not move and are not actively aggressive, they will damage Link if he touches them. He must push them out of the way using his Shield in order to reach his washed up Sword. He can then use his Sword to destroy them with a single hit.

In, the four Links cannot push or destroy them with any weapons. Instead, they are forced to either simply avoid them, or defeat other enemies in the area in order to make them disappear.

(Cagiva)
A single Sea Urchin is seen on Toronbo Shores blocking the access to Link's Sword. Being chased by Octoroks, Link dashes and bounces off the Sea Urchin using his Shield to reach his Sword.

Super Mario Maker/Super Mario Maker 2
Sea Urchins are seen in Super Mario Maker and its sequel where they can be placed in the Super Mario World underwater level style, replacing the Spike Traps. While the name is not mentioned in the first game, the second game does mention it.

Trivia

 * states that Sea Urchins will attack Link. Despite this, Sea Urchins are unable to move.