Sponge

A sponge was a tool for cleaning through absorption.

The Kith were a highly-evolved, sponge-like, myconid race with tendrils in the place of arms. (AUDIO: Max Warp)

The radiation sponge was a sponge-like, alien object owned by Torchwood Three. Though it looked like a normal loofah, it was capable of absorbing six types of radiation and was so effective it needed to be kept in a lead-lined case. (PROSE: Another Life)