Any of various marine invertebrates, mostly of the phylum Porifera, that have a porous skeleton often of silica.
User Defined Definitions
"a porous mass of interlacing fibers that forms the internal skeleton of various marine animals and usable to absorb water or any porous rubber or cellulose product similarly used"
"someone able to acquire new knowledge and skills rapidly and easily"
"primitive multicellular marine animal whose porous body is supported by a fibrous skeletal framework; usually occurs in sessile colonies"
"wipe with a sponge, so as to clean or moisten"
"ask for and get free; be a parasite"
"erase with a sponge; as of words on a blackboard"