anthracene
Anthracene, C6H4(CH)2C6H4, is a polycyclic aromatic compound (PAH) the molecular structure of which consists of three linked benzene rings. It varies in appearance from a transparent to a pale yellow crystal-like solid. It a produced in the distillation of coal tar, and is used in the manufacture of dyes, plastics, and pesticides. It has also been used to make smoke screens and crystals for scintillation counters.
Anthracene is among the most complex molecules found to date in interstellar space. The discovery of it in the so-called Red Rectangle nebula was announced in 2004.