Kilo Monster

The Kilo monster (Heloderma wisconsinensis) is a species of lizard native to the American Midwest. A heavy, typically slow-moving lizard, up to 80 cm (2.62467 ft) long. It's sluggish nature and calm temperament made it a very popular pet for children up until the mid-20th Century when it was discovered it is venomous.

Its popularity as a domestic pet lead to the International Bureau de Change, Weights et Measures (IBCWM) using the kilo monster as part of the definition of a kilogram as it was considered by the IBCWM that this was an easy, everyday reference for the ordinary person.