Eye of newt

An ingredient formerly used in teleportation spells. This ingredient fell out of use on Earth after polyethylene became easily available in the 1950's. (It was invented much earlier, in the 1930's, but -- due to difficulties with the manufacturing process -- for a long time could only be made in very small amounts in the lab.) Polyethylene "interrupts" the structure of spacetime in almost exactly the same way that eye of newt does, and so makes an excellent substitute.

There are people who will say that using eye of newt is more environmentally friendly than using polyethylene. There are only two things to say to such people: (1) They wouldn't say that if they were newts. (2) They plainly have never had to spend days and days finding the right kind of newt¹....and then they haven't had to try to talk the newt out of one of its eyes. (HW)

(See also: Ingredients in spells: Theoretical wizardry.)

¹Neuerurgus kaiseri, the "Kaiser's Spotted Newt" or "Luristan Newt".