Hardhat Beetle

Hardhat Beetle is a recurring jellyfish-like enemy with a bouncy shell in the Zelda series. They mostly appear in the 2D titles where they serves as obstacles meant to make Link bounce into pits or various other traps.

A Link to the Past
Hardhat Beetles made their debuts in The Legend of Zelda: A Link to the Past where they appear in most dungeons and in the caves of Death Mountain. They are usually in group and will start to move toward Link as soon as he enters a room. They can be killed but any direct hit will cause them as well as Link to bounce backward. The safest way to deal with them is by pushing them into pits with ranged weapons. Blue Hardhat Beetles are the weakest of the two typês found in the game. Red Hardhat Beetles have more health and are faster to close in than Blue Hardhat Beetles. Bombs can also stun them.

Link's Awakening
In The Legend of Zelda: Link's Awakening, they are invincible to almost all weapons. Link is no longer pushed back when hitting them with his sword so he can hit them with it until they fall into a pit. Bombs will now kill them.

Oracles
In The Legend of Zelda: Oracle of Ages and The Legend of Zelda: Oracle of Seasons they are still invincible and retain their weakness to bombs as well as their bouncing mechanics. In Oracle of Seasons they can also be destroyed by using the Magnetic Gloves to crush them with metal balls.

Four Swords Adventures
In The Legend of Zelda: Four Swords Adventures they are similar to their A Link to the Past appearance but can now even bounce when they touch eachothers. The main way to defeat them is once again pushing them into pits but they can also be killed by performing a Down Thrust after using Roc's Feather.

Phantom Hourglass
In The Legend of Zelda: Phantom Hourglass, Hardhat Beetle start appearing from the Temple of Courage onwards. They are once again immune to most weapons and the best way to get rid of them is by pushing them into pits. They can now be defeated by the Hammer.

A Link Between Worlds
In The Legend of Zelda: A Link Between Worlds, they appear in the Tower of Hera, the Treacherous Tower, and in the Ice Ruins. They are similar to their A Link to the Past incarnation but they push Link way farther when he touches them. Using the Hammer next to them will also stun them due to the shockwaves.

Tri Force Heroes
In The Legend of Zelda: Tri Force Heroes, there is two varieties of Hardhat Beetles. The blue onces are essentially the same as their A Link Between Worlds incarnation but the red ones are on fire and require the use of certain items such as the Gust Jar to remove the fire and push them into a pit.