sponge

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

A follower who hangs around a host (without benefit to the host) in hope of gain or advantage

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

Soak up with a sponge

Gather sponges, in the ocean