Much has been written about the imperfections of the fossil record, and how unless they are resurrected, science could offer educated guesses at best as to the colors of extinct pokemon. This did not whatsoever lessen the shock among the scientists at Devon Corporation when, having brought one to life for the first time in one hundred million years, they discovered that Lileep were actually purple.
This discovery has revised a great deal about our understanding of Lileep, and given cause to wonder how much insight humans can truly have into so distant a past. Lileep were believed to be camouflage hunters who disguised their bodies as water and their roots as seaweed, but barring remarkably poor vision on the part of their prey, their strange color would have given any such trap away. The other hypothesis of the time, that the Lileep were green from chlorophyll, is true of a tiny minority of resurrected fossils and of their evolved form of Cradily, but the lack of green in normal Lileep makes this hypothesis untenable.
If they were not powered by the Sun or predation, only one explanation remains, one more suited to undying pokemon than those capable of death and reproduction. Lileep were remarkable for their ability to anchor themselves to the ground, and have recently shown themselves capable of healing damage at a remarkable pace when sufficiently ingrained. Most believe that Lileep absorbed energy from rocks which fall into the ocean, and that they somehow managed to obtain all their nutrition by digesting natural minerals alone. Others, citing their lack of water attacks, have wondered if they were truly deep-sea pokemon at all, and suggested they had a custom of ocean burial and avoided the need for sunlight by preying on the distant ancestors of Onix and Geodude.