Preparing large cherrystone clams
An oyster knife, paired with the most common technique used to open oysters will fail you when it comes to clams.  You need a thinner bladed, clam knife...and you need to find the seam opposite the hinge side of the clam.  Another approach is cryo-shucking; that is, freezing for a short time in a traditional freezer...or even using liquid nitrogen, if it is available.  Large cherrystone clams can be steamed.  I prefer them raw...or opened, seasoned and baked, such as in clams casino.  If they are very large, approaching the size of quahogs, steam them open, chop them up and make chowder.