There is now abundance of these stone crabs in New York City, no need to fly to California or Florida. Simply steam them for seven minutes and make a nice dipping sauce with a touch of salt, chopped red birds eye chiles minced with a squeeze of lime juice, mix in a few tablespoons of water and Nuoc Mam (fish sauce). If you have sprigs of cilantro handy chop them in.
How to check if they are fresh? Simply turn the crabs upside down and check for freshness by their movements and no tiny bubbles being blown out from their head. After purchasing, keep in brown bags away and hold in fridge until ready for steaming. Yum!