Bring 2 inches of water to a boil in a 16-quart stockpot over high. Add 3 ears corn in a single layer, and top with 6 lobsters. Cover and steam until lobster shells are bright red and you can distinctly smell cooked lobster in the air, 14 to 16 minutes. Remove cooked lobsters and corn to a rimmed baking sheet. Return the water to a boil, and repeat with remaining 3 ears corn and 6 lobsters. Serve lobster tails, crusher claws, and corn with melted salted butter.