sponge

noun

1
primitive multicellular marine animal whose porous body is supported by a fibrous skeletal framework; usually occurs in sessile colonies
2
a follower who hangs around a host (without benefit to the host) in hope of gain or advantage
3
someone able to acquire new knowledge and skills rapidly and easily
she soaks up foreign languages like a sponge
4
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

Also useful for “sponge”:Unscrambler— Rearrange the letters in “sponge”