I've seen much conflicting advice in print on the purging of shellfish. Some of this may reflect the possibility that they were foraged from sea sites. My foraging all takes place at the fishmonger's shop. For store bought shellfish (in US) is any purging required/desirable. If so, how and how long? (I've read soaking in water, salt water, and cornmeal in water, etc. - very confusing).