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 or strange hearts with a pick. 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 Astelleron, who'd discovered and researched its 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. Its blood was first used to resurrect Adjhar, then again with the addition of a golem heart for Bollux.

Trivia

 * One regular problem players encounter is, how to actually "milk" the stone for blood and the heart. For the blood, a bucket has to be placed in the south-eastern part of the stone, then the pickaxe has to be equipped and then used (not attack) on the tree on the stone. The same goes for the heart, after getting the information from Adjhar.
 * A Guide to the Isle of Fire clearly states the stone golems were present on the island before Erethian raised it from the sea, while Astelleron's logbook suggests the island was still above the waves at the time of the golems' creation.