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 ", for example sea glass being referred to as "forbidden fruit snacks". Calamari is fried squid, referring to the Moon Lord's cephalopod appearance.
 * The pet itself marginally resembles the Ancient Vision, an enemy summoned by the Lunatic Cultist.
 * The buff tooltip, "A friend from beyond", is a reference to H.P. Lovecraft's short story "From Beyond", which is a story of a man who witnesses alien creatures in alternate dimensions.