Was this ancient vessel a hand grenade? If so, it backs up a long-debated theory about weapons in the Crusades
Much is known about life in the Middle East at the time of the Crusades, but one type of vessel still presents something of a mystery.
These ceramic artefacts are called sphero-conical vessels – a term describing their shape – and hundreds have been unearthed across the region.
"There's a range of sphero-conicals, from thin-walled ceramics that could be used for drinking vessels, mercury containers, and all different sorts of stuff," says Professor Matheson.
"But these ones are thick-walled ceramics that we call stoneware. Small containers, small content, withstanding high pressures.
Professor Matheson believes this fourth fragment, or sherd, is from a hand grenade used during the Christian Crusades — the religious wars initiated by Christians intent on reclaiming the Holy Land from Islamic rule.
In naval warfare the Byzantines famously used flame throwers to project a fluid known as "Greek fire", the precise ingredients of which were kept a military secret and remain a mystery to this day.
