Long before loofahs, shower poufs, and washcloths, folks placed soap cakes in felted wool covering.
It decreased the problem of slippery soap.
It was lightly exfoliating, but still soft like a washcloth.
The wool has antimicrobial and antibacterial properties.
Felted soap lasted longer!
The idea behind these is that, as the soap shrinks with use, the wool felts through rubbing and the use of hot and cold water.