Meteor Head

Meteor Heads are flying enemies which spawn when you enter a meteorite's crash site. They usually spawn in packs of 3-5 and will override other enemies in the area, meaning that no other enemies will spawn as long as there are Meteor Heads around.

Meteor Heads follow typical Flying AI with an override exception, meaning they do not collide with solid blocks and can fly straight through them.

A suggested way of killing these is to use a Pickaxe such as a Nightmare Pickaxe or a Molten Pickaxe. While mining, you can hit the Heads while they fly at you, as long they're coming from one direction. Cobalt Shields will help you stand in place so you can mine the Meteor easier. A Grappling Hook or Ivy Whip can be used in place of a cobalt shield to hold a miner in place, and Shadow Armor or Feral Claws can increase your pick's swing rate to help keep the little buggers at bay.

Another suggested tip, the heads do not respawn instantly, meaning if you pull out a larger weapon, such as The Breaker you should be able to kill all of them rather quickly, provided they have grouped up, and then quickly down a health potion, or position your next grapple before they are able to respawn and attack you again.

As is suggested in the video, an Obsidian Skull can help in dealing with the meteor heads, because a lot of the damage while mining meteorites may come from being knocked onto the meteorite itself.

Meteor Heads will stop spawning once there are only 49 or fewer blocks of the meteorite left, usually about 10-20% of its total size.