Several species of Hymenaea, including jatobแ, produce usable copal resins. At the base of the jatobแ tree an orange, sticky, resinous gum collects, usually underground (however, the bark also produces smaller amounts of resin when wounded). The resin of Hymenaea trees converts to amber through a remarkable chemical process requiring millions of years. During this process, volatile plant chemicals leach out of the resin and other non-volatile chemicals bond together. This forms a hard polymer that is resistant to natural decay processes and the ravages of time. As portrayed in the Jurassic Park movies, amber of million-year-old Hymenaea trees have provided scientists with many clues to its prehistoric presence on earth as well as to the insects and other plants encased in it.