After several weeks, the parasitic larval form is released and develop into free-living clams. Mussels use gills like fishes to breathe underwater. The water taken in through the siphons for food passes through their gills to deliver the oxygen mussels need to survive. The gills are thin plate-like structures that remove the oxygen that is dissolved in the water. A mussel can be identified by it s outer shell.
Mussels shells within the same species closely resemble one anothers.
Thus, by examining the mussel s shell, you can identify what type of mussel it is.