Bezoar

A bezoar (/ˈbiːzɔər/, from Persian bazahr, "antidote") is a mass found trapped in the gastrointestinal system (usually the stomach),[2] though it can occur in other locations.[3][4] A pseudobezoar is an indigestible object introduced intentionally into the digestive system.[5]
There are several varieties of bezoar, some of which have inorganic constituents and others organic.

Bezoars were sought because they were believed to have the power of a universal antidote against any poison. It was believed that a drinking glass which contained a bezoar would neutralize any poison poured into it. The word "bezoar" comes from the Persian pâdzahr (پادزهر), which literally means "antidote".

source: http://en.wikipedia.org/wiki/Bezoar