Wyrm's Heart
Appeared in Ultima VII part II (the Serpent Isle) as a requirement for cold based spells. Said to be taken from Ice Wyrms.
Was to be used as a Necromancy reagent in Ultima Online, but the original design for Necromancy was scrapped. Wyrm's Hearts appeared in-game, but as very rare spawns, as part of a set known as Pagan Reagents. On most Shards a Wyrm's Heart is worth a good deal of money.