Vacuole

Vacuoles are organelles found in eukaryotic cells that consist simply of a membrane bound bubble. There are various different types of vacuoles, used for different things. Most notable are food vacuoles, which contain ingested material prior to digestion (not unlike a bird's crop); lysozomes, which contain enzymes; and contractile vacuoles, which collect water from within the cell and expel it (the cell's bladder, of course).