Sponges do not naturally exhibit the fresh, golden appearance that they have when modern consumers buy them from stores. In fact, when divers first bring them up from the sea they are black and rather unpleasant. A systematic process of washing and pressing the sponges must be followed in order to break down their external membrane and tissues. When only the skeletal fibers of the creatures remain, they are trimmed, dried, and frequently immersed in a mixture of water and hydrochloric acid, a procedure that gives them a blonde coloring, before being sold by merchants.