The term 'Large Crustacean' can be summarized by two crossword solutions: PRAWN (5 letters) and LOBSTER (7 letters). Prawns are a type of seafood that are related to shrimp and have a sweet, delicate flavor. They are usually cooked and eaten whole. Lobsters are also a type of seafood, but they are larger than prawns and have a more intense flavor. They are usually boiled or steamed before being served. Both prawns and lobsters are considered large crustaceans.