For those who eat shellfish, many find this one a tasty treat, especially roasted with butter, but it’s important to be careful when harvesting this one for dinner. Certain times of the year, typically late spring through late summer, these filter feeders can accumulate a toxic microorganism, which can temporarily build up in their tissue. Sea stars, birds, some marine snails and even raccoons find the California mussel to be a nutritious part of their diets.