Greek fire

"Greek fire" was a formula for a substance that the Byzantines possessed, which was allegedly capable of burning underwater. Sulphur was one of its ingredients.

In the 12th century, the scholar Moses of Tyre investigated various alleged recipes for the substance and cross-referenced them to try to reconstruct the original. However, he did not test his theories until he moved to England and was asked under pressure to create a large quantity of Greek fire to defeat a Krynoid which had partially embedded itself in the moat of Earl Godfrey's castle, meaning boiling oil or flaming arrows would not suffice to burn it away. The substance Moses ultimately created, adding charcoal and other elements to the classical recipes, was something new, more potent and explosive, which handily dispatched the Krynoid. (AUDIO: The Green Man)