''Sphaeroma pulchellum'' is a species of

isopod Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, an ...

in the family Sphaeromatidae. It can be found in the Black Sea where it curls into small spheres on the sandy benthos.

References

Sphaeromatidae Fauna of the Black Sea {{Isopod-stub