PRESERVED_SPECIMEN; ; 70% alc.; microslide; HYPOTYPE. See: Dana, James D. 1854. Catalogue and descriptions of Crustacea collected in California by Dr. John L. Le Conte. Proceedings of the Academy of Natural Sciences of Philadelphia. 7: 175-177.; IZ number 290; lot count 30; Microslide 01, balsam, appendage(s); other number 25;
This is also called a kelp isopod, and can be different colors. The only thing that bothers me is that it does not have the rounded abdomen. An amphipod is flattened laterally, while an isopod is flattened dorso-ventrally like this arthropod.