Piece of Moon Squid

Type	Pet summon
Use time	20 (Very fast)
Tooltip	Summons a Moonling; 'The forbidden calamari.'
Rarity
Sell	5 GC
Research	1 required
Buff	Moonling(Desktop, Console and Mobile versions)
Buff tooltip	A friend from beyond
Use	https://terraria.wiki.gg/wiki/File:Item_2.wav

Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.

Master Mode-Only Content: This information applies only to Master Mode and Master Mode worlds.

Not to be confused with the Suspicious Looking Tentacle.

The Piece of Moon Squid is a Hardmode, post-Moon Lord pet-summoning item that spawns a Moonling, which resembles the Moon Lord's head, that follows the player. The Piece of Moon Squid has a 1/4 (25%) chance of being dropped by the Moon Lord in Master Mode.

Trivia

The Piece of Moon Squid's tooltip, "'The forbidden calamari.'", is likely a reference to a common internet meme, where some form of an object similar to food, which in reality is not edible, is nicknamed "Forbidden <food>", for example, sea glass being referred to as "forbidden fruit snacks". Calamari is fried squid, referring to the Moon Lord's cephalopodic appearance.
The Moonling may be a reference to Inklings from the third-person shooter video game series Splatoon.
The Moonling itself marginally resembles the Ancient Vision, an enemy summoned by the Lunatic Cultist if the player attacks a duplicate of the Lunatic Cultist while the Phantasm Dragon is still alive.
The buff tooltip, "A friend from beyond", is a reference to the 1920 short story "From Beyond" by American writer H.P. Lovecraft, which is a story of a man who witnesses alien creatures in alternate dimensions. The Moon Lord, which the Piece of Moon Squid drops from, also happens to be a reference to H.P. Lovecraft – this time, the cosmic entity Cthulhu, a fictional character Lovecraft created.