Drain the clams and set aside on a paper towel. Heat the oil in a skillet and saute the scallions, parsley, capers, and mushrooms over medium heat
for about 5 minutes.
Remove from the stove and stir in the lemon juice and the cracker crumbs. Mash the egg half, both the white and the yolk, and stir it into the saute mixture along with the clams. Season to taste with salt and pepper.
Lightly grease 4 scallop shells, and fill with the clam mixture. Heat for 4 or 5 minutes in a preheated 400-degree oven, and serve immediately.