Shrimp and Rice Casserole

2 medium celery stalks , cut lengthwise in half, then thinly sliced crosswise

1 large onion , chopped

1 medium green pepper , cut into 1/2-inch dice

2 clove(s) garlic , minced

5 teaspoon(s) dried thyme

1/4 teaspoon(s) ground nutmeg

1/4 teaspoon(s) ground red pepper (cayenne)

2 cup(s) aromatic rice , such as Texmati 1 1/2 pound(s) medium shrimp , shelled and deveined, with tail part of shell left on if you like 1 bottle(s) (8-ounce) clam juice

1 1/2 teaspoon(s) salt

1 bay leaf

3 plum tomatoes , seeded and sliced