How do you determine an off or rotten inedible mussel before cooking?

Visual Inspection:

* Shell: Look for closed shells. If a mussel is open, try gently tapping it. If it closes, it's probably fine. If it stays open, it's likely dead.

* Smell: Fresh mussels should have a clean, briny scent. If they smell fishy, ammonia-like, or sour, discard them.

* Appearance: The flesh should be plump and firm, not dry or mushy. The outside of the shell should be free of cracks, chips, or damage.

Other Signs:

* Broken Shells: Broken shells can allow bacteria to enter, making the mussel unsafe.

* Mussels with "Beard": The long, thin threads called "beards" should be present. If they are missing, the mussel may be old.

Important Notes:

* Never cook mussels that are open and don't close when tapped.

* Discard any mussels that have a foul odor.

* Always cook mussels thoroughly to kill any bacteria.

Safe Handling:

* Refrigerate mussels until you are ready to use them. Store them in a single layer in a bowl with a damp paper towel or cloth.

* Don't wash mussels until right before cooking. Washing them too early can cause them to die.

* Always check mussels for freshness before cooking.

If you have any doubts, it's always best to err on the side of caution and throw out any questionable mussels. Enjoy your delicious and safe seafood!