sponge

noun

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