SPONGE (σπόγγος, G5074, sponge, all Eng. VSS). The only occurrences (Matt 27:48, etc.) concern the drink of vinegar given to the Lord on the cross. Sponges, of the phylum Porifera, are lowly marine animals whose horny skeletons have been used for a variety of domestic purposes since very early times. According to Pliny it was standard practice for Rom. soldiers to carry a piece of sponge for use as a drinking vessel, precisely as described in the gospels.
International Standard Bible Encyclopedia (1915)
The word "sponge," the Mt 27:48; Mr 15:36; Joh 19:29. Sponges have been known from the earliest periods. They are mentioned by Homer, Aeschylus, Aristophanes and other ancient writers. The sponge fisheries of the Eastern Mediterranean are still among the most important in the world. Sponges are animals of a very simple organization, fixed to rocks or other objects in the sea or in fresh water. The marketable sponge consists of a mass of soft interlacing fibers which constituted the skeleton of the living animal. The sponge fishers of the Levant dive from boats, with or without diving apparatus, and tear the sponges from the rocks with their hands. The sponges are allowed to die and rot in the air and are then thoroughly washed until nothing but the skeleton remains. Sponges which have calcareous or silicious skeletons are unfit for use.