Shiftslime, commonly referred to as "Changeling Goo", is an all-purpose substance naturally produced by changelings prized for its abundance and utility. Changelings proudly profess that the substance has "a million and one different uses", as the nature of shiftslime can change on a whim with small inputs of changeling magic. It is commonly used as or in sealants, adhesives, lubricants, medicine, narcotics, cooking, utensils, filters, non-changeling transformations, imprisonments, incubations, love extractions, thermal insulation, electrical insulation, and construction amongst countless other uses. New uses are discovered often.

In areas heavily populated by changelings, it is commonly said that one is no less than a few metres away from a deposit of shiftslime, and a creature unfamiliar with the ever-shifting environment may find themselves running into a lot of the stuff. No wonder ponies hate visiting the Changeling Lands.

[alt source](https://www.newgrounds.com/art/view/moonatik/goo-d-up)