Shrimp Or Crab Delight

1 pkg. Knox gelatin

3 T. water

1 can mushroom soup

6-oz. cream cheese

1 c. chopped celery

1 small onion, grated

1 7-oz. can shrimp or crab

3/4 c. mayonnaise

Dissolve the gelatin in the water. Heat the soup to warm and add gelatin mixture. Mix all the ingredients together and pour into a mold. Refrigerate overnight. Be sure to rinse shrimp or crab with water to remove salt. To serve: unmold and serve with crackers.