Gnat trapped in amber. Gall gnat (family Cecidomyiidae) fossilised in Baltic amber. Amber is a fossilized resin that was produced by various now extinct coniferous trees during the Jurassic period. The sticky resin trapped small insects as it solidified and hardened, preserving their bodies for millions of years. This is one of the few processes by which fossils are preserved complete with all of their soft tissues.