I'll add my own pic the next time I buy clams, but this Youtube shows my problem.
I buy clams at Pusateri and Whole Food Market for a year in Toronto. They sell them on ice, not in running water.
Place all the clams in a bowl and fill it with cool tap water. We’ve also heard that adding cornmeal or black pepper to the water will encourage the clams to spit out more sand.
Let the clams sit for 20 minutes to an hour. During this time, they will spit out the sand from inside their shells.
When you’re ready to cook, lift each clam from the water and scrub it to clean any particles or grit from the outside surface. It’s better to lift them individually because straining them into a colander would dump the sand back on top.
I repeat this 6 times...so 20 mins x 6 times = 120 mins of soaking!!! Clams exudate less grime every next time, but even after 6 times, water still has much grime! Why? This happening for a year!
I know I ask similar question for mussels but clams different! Clams don't have byssus.