Viral Meteorite Ore is a post Skeletron ore
Upon defeating Skeletron, the message "A dangerous virus now inhabits (world name)" will appear the next in-game morning, signifying the viral meteor has landed. Although it spawns exactly like a normal meteor, unlike vanilla meteorite, you will not take damage from standing on top of the ore. Viral Meteorite is used in crafting Viral Meteorite Bars and Viral Powders. You must have at least a Nightmare or Deathbringer Pickaxe in order to mine the meteor. Anything better will also suffice. Viral Meteorite ore will spread to normal meteorite allowing you to gather more.