Companion Cube

The Companion Cube is a summoning item sold by the Travelling Merchant for. It summons a pet Companion Cube. When it falls into lava, it emits the sound of the Lunatic Cultist when he has been defeated. It is possible that the cube emits the Whoopie Cushion sound, and damages you, but this is to be further tested.

Trivia
The idea of the companion cube was first introduced in the game Portal.

History
Cube de Voyage