Piece of Moon Squid

The Piece of Moon Squid is a pet item that has a chance to drop from the Moon Lord in Master Mode. It summons a pet Moonling that resembles The Moon Lord's head.

Trivia

 * The item's tooltip, "The forbidden calamari", is likely a reference to a common internet meme, where some form of object similar to a food, which in reality isn't edible, is nicknamed "Forbidden ". Calamari is fried squid, referring to the Moon Lord's cephalopod appearance.
 * The pet itself looks very similar to the Ancient Vision, an enemy summoned by the Lunatic Cultist.