Isonucleic residue
Isonucleic residue was a brown and sticky substance. ()

It could contaminate warp plasma, with concentrations of 20 parts per million being enough to label it far from pure. ()

In 2385, the A500 android F8 did not understand a joke posed to him that asked "what's brown and sticky," and responded by listing substances including isonucleic residue. ()
Materials