According to legend, it possessed the key to immortality; if a special brew (which included a piece of Gargoyle stone skin in its ingredients) was made in it and someone bathed in it afterwards, that person would live "as long as the mountain stones." The stone skin had to boil in the special brew for a night and a day before being used. In fact, the brew would turn anything dipped in it into stone, or more accurately, the same organic substance that gargoyles become during the day.
Xanatos obtained the Cauldron of Life and decided to use it as a means of becoming immortal, capturing Hudson to use both as a source for the necessary piece of stone skin, and as a guinea pig. When Hudson escaped, Owen volunteered to test it, and dipped his hand into the Cauldron's brew; his hand was promptly turned to stone. Xanatos was mildly disappointed, but out of his usual desire not to waste anything, he melted the Cauldron down and used it to create Coyote 4.0., intending to use this robot's iron composition as a means of turning it into a "Kachina trap", particularly for Coyote the Trickster. This also failed in the end, however. Whether Xanatos recovered the resulting wreckage of the robot for the metal of the cauldron is unknown.
The Cauldron is a large iron pot several feet across and clearly quite heavy. It is appropriate that a gargoyle's stone skin is linked to immortality, since while in such a state gargoyles do not age and all biological processes cease. Thus, Owen's hand is not stone, but is organic and is in the same state that the gargoyles were in when frozen in sleep by the Magus. Owen's hand is still alive in a sense and does not suffer from erosion. So ironically, if someone were to bathe in the Cauldron, they could conceivably live longer than the mountain stones. Whether the person would be reanimated by night like a Gargoyle is unknown.