The Anima Mundi is sacred to the gnomes, for they believe Guthix created it when he shaped Gielinor in the First Age. The Anima Mundi seems to be an integral part of the world itself, without which it cannot exist. At the end of the Third Age, the world had been so ravaged and scarred due to the atrocities of the Gielinorian God Wars, that the Anima Mundi itself cried out in agony and pain, waking Guthix and prompting him to banish the young gods.
The Anima Mundi is very important to the spirit trees, as they use it not only as a means to survive, but to commune with one another as well. If they are separated from the Anima Mundi, they become weakened and corrupted, and slowly lose their life force until they die.
There have been few throughout the world's history that have attempted to experiment with this force, as doing so is not only dangerous and nearly impossible, but considered an unholy act that goes beyond mere evil. One gnome, Glouphrie, is known to be conducting experiments involving the Anima Mundi within his hidden city, Arposandra. This has allowed him to create large amounts of warped terrorbirds and warped tortoises, amongst other things.
Apparently, interfering with the Anima Mundi creates massive amounts of waste material, as is evident in the Poison Waste in southern Isafdar. It is here that Arposandra dumps the sewage made by its experiments, which slowly destroy more of Isafdar each day. The substance itself is very sticky and full of explosive chemical compounds. It has also made the area's life energy very weak, and nearly caused the death of at least one spirit tree.
It is implied in the Path of Glouphrie that Seren, usually considered the goddess of the elves, is the divine aspect of the Anima Mundi. When Guthix died, the Anima Mundi mourned him in the form of crying trees.