These little crustaceans go by a lot of names. This looks like the common wood louse to me (Oniscus asellus). I've always called them wood louse but I quite like the name Pill Bug - maybe because they roll up like a (spherical) pill??
All these photos are of the same one: a female; she was holding eggs in the pouch on her underside.
|Great little armadillo|
She was in our compost bin. Wood lice are good for compost bins and very welcome as they eat a lot of cellulose which is normally slower to break down.
It doesn't take much to make them roll up in a ball.