Possibly an amphipoda, a shrimp like crustacean. There are several species such as Pelagic/ Terrestrial. Most are water dwellers but the Terrestrial can be located on sand, pebbles or beaches.
There are many bugs that look like shrimps and the most common are isopods and the next most common shrimp looking bug is the lawn shrimp bug, many varieties can be found according to location and temperature conditions.
