Some endemic plant species are categorized as "carnivorous", which are thus the food supply (mainly insects) that are so scarce in the mountains. These have a geological formations ranging between 1.5 and 2 billion years, which makes them one of the oldest formations in the world. The best known tepuies are: the Auyantepuy (where it follows the Angel Falls), the Roraima, the Kukenan and the Chimantá among many others.[3][4]