Wash and chop celery. If using fresh shrimp, peel and clean; if using cooked frozen, rinse and pat dry. For fresh shrimp, cook in a pot of boiling water and cook until shrimp turns bright pink, about 3-4 minutes. In a medium mixing bowl, combine shrimp, chopped celery, black pepper, lemon juice, mayonnaise, and curry powder. If desired, cover and chill in the refrigerator ~1 hour, to allow flavors to blend. Serve over salad greens.