It's simply a savory gelatin crab salad mold made with mushrooms soup, some cream cheese, mayonnaise, celery, green onions, seasonings and, of course, crab. You can also substitute shrimp for the crab and tomato soup for the mushroom - or so I've heard, I've never tried that version because I love the crab one.
I think this one's been around to categorize it as a classic - maybe even comfort party food but people still love it. It's always the first dish at my parties that disappears. Try it out at your next party served with some great crackers or toasted french bread slices.