What is an animal that is an invertebrate and has bilateral symmetry?

All arthropods, which are invertebrates, have bilateral symmetry. Arthropods include all insects, centipedes, millipedes, crustaceans and arachnids.

Bilateral symmetry means something has symmetry across one plane (known as the sagittal plane, and directly down the centre of their body), which means one side of their body approximately mirrors the other side.