Locke looked into its eyes. Mr. Eko stared into its heart. The "Monster", aka security system is one of the many unsolved mysteries of Lost. Damon and Carlton have promised more of it next season, and hinted that we may have seen it in season two but didn't realize what it was. Whatever it is, this tree rustling, ground shaking thing is still an enigma to the survivors.
Community content is available under CC BY-NC-ND unless otherwise noted.