If you're not buying it cooked, buy it alive — it's the only
guarantee of freshness. Look for moving legs, claws, antennae,
and, in the case of lobster, a flipping tail.
Stone crabs and king crabs are usually sold cooked — sometimes
frozen, sometimes thawed. A live-cooked lobster will have a tail
that curls back with a snap. These are all best served cold, since
reheating toughens the meat.
You can keep live lobsters and crabs chilled and moist (covered
with water-soaked newspaper) in the refrigerator for up to one
day.
Plan on one one- to two-pound lobster or four to six hard-shell
crabs per person.
