The most highly valued pieces of amber contain encased plant matter or organisms, called inclusions. These amber pieces are veritable time capsules, providing us with a glimpse into the past, an opportunity to observe prehistoric flora and fauna.
The majority of inclusions come from the insect family (arthropoda). Most of the creatures found were highly active, living in and on tree bark or on the forest ground. Flies, spiders, centipedes and termites are among the more common inclusions. Vertebrates are rare, but a few amphibians and reptiles, even small mammals have been found.
How did these creatures get inside the amber? After falling into or landing on the sticky resin, the creature was trapped. Any attempt to free itself only made it sink deeper into the resin. Once the dead creature had been completely covered by subsequent resin flows, the process of mummification began until all fluids had left the body. The resulting fossils are preserved in minute detail.
What is visible is the empty casing or shell of the body, while the body cavity itself is usually empty. In rare cases, the internal structure of the inclusion has remained preserved, meaning that the body was completely encased in resin with no fissures exposing it to the detrimental effects of oxygen.