Rubber
Rubber was a type of stretchy material made from a secretion of the rubber tree. It was used to make rubber bands. 

Because of its non-conductive properties, it was used for the s of shoes worn by researchers experimenting with electricity. In 2365 while playing Sherlock Holmes Program 3A, Data, as Holmes, noted that a set of footprints left behind bore dark markings from these kinds of soles. ()

See also
 Gutta percha
Rubber Tree People

External link

Biochemical compounds