The Mackled Malaclaw is a land creature closely resembling a lobster. The Malaclaw has light grey skin with green spots, and can reach a length of twelve inches. Although it resembles a lobster, it is unfit to eat, and anyone who eats flesh of a Malaclaw will come down with a nasty fever and develop a green rash.
The Malaclaw is found along the rocky coastline of Europe and dines mainly on crustaceans. A bite from a Malaclaw has the unusual side effect of making the victim unlucky for up to a week. Any witch or wizard bitten by a Malaclaw should call off all bets, wagers and ventures since they will definitely go against him.
- Fantastic Beasts and Where to Find Them (First appearance)