They can grow up to 24 centimetres long — nearly the length of a dinner plate — making them one of the largest mussel species anywhere in the world.
Greenshell mussels are steamed in their distinctive green-lipped shells, often with white wine, garlic and cream, and served in the shell with bread to mop up the broth. The small Marlborough Sounds town of Havelock — self-declared 'Greenshell Mussel capital of the world' — grows and serves them straight from farms just offshore.