1. Chop calamari tentacles; cut body into 1/2-in. rings.
2. In a large saucepan, heat oil over medium heat. Add anchovies if desired; stir in parsley and garlic. Cook 1 minute. Add wine; stir in mushrooms, if desired, and seasonings. Add calamari; bring to a boil. Reduce heat; simmer, covered, until calamari is tender, 2-3 minutes. Remove pan from heat; cool slightly.
3. In a serving bowl, toss celery, olives, lemon juice and calamari mixture. May be served warm, or refrigerated and served cold.
