Seafood Spheres on Crostini

Name: Seafood Spheres on Crostini
Ingredients: 2 tablespoons finely diced celery; 1 tablespoon freshly chopped flat-leaf parsley; 2 teaspoons freshly chopped thyme leaves; 1 lemon, zest, finely grated; 1/2 cup mayonnaise; 1/4 pound smoked salmon, chopped fine; 1/4 pound cooked lobster meat; 1/4 pound cooked crabmeat, picked through to remove remnants of shells; Salt and freshly ground black pepper; 1/2 loaf French bread, sliced into 16 (1/2-inch) slices and lightly toasted; 16 small parsley sprigs, for garnish