The sponge is a plant-like animal that lives on the ocean floor. It absorbs nourishment from water passing through its body. When a sponge is removed from water, the cells die, leaving a skeleton. The skeletons of some sponges are flexible and porous. These have been used for centuries as cleaning and water-absorbing tools. Such a sponge, dipped in sour wine, was offered to Christ on the cross (Matt. 27:48; Mark 15:36; John 19:29).

Source: [Anon-Animals]