Year 10.000 to Present
There is a giant worm. Though he resides in Sterilis, there is a mention of him in Lake Torra. Every month, this long desert worm burrows his way from the desert to Lake Torra to drink. Then burrow back. This, of course, leaves quite a hole near a grouping of boulders. If one were to follow, they would find themselves under Sterilis. Keep in mind, the sand collapses behind him, so that is as far as you would get.