Stone of Castambre

The Stone of Castambre is truly an enigma. Standing on the Isle of Fire in Britannia, it is a bleeding stone from which a tree grows. The Stone can be "milked" for blood and/or strange hearts. Both of these items are needed in the act of Golem creation or reconstruction. Otherwise, there isn't really much known about the stone, apart from a book on the Isle of Fire, written by the mage who'd discovered it's use in the creation of Golems.

The Stone played a major role in Ultima VII, where it was needed to heal the two Golems on the Isle of Love, Adjhar and Bollux in the Test of Love.