Waterorb

Waterorb was a fungus that grew in the Underdark in shallow water. When mature, it was bulbous in shape and bigger than a human head. If squeezed and wrung out, it yielded about a gallon (almost four liters) of potable water. The remaining husk was bland and chewy like a sponge, but edible, providing about a pound (almost a half kilogram) of food.