Heat 3 tablespoons olive oil in a large skillet over medium heat; cook and stir sea scallops, shrimp, and calamari rings in the hot oil until scallops and calamari are opaque and shrimp are pink, about 5 minutes.
3
Bring a separate pot of water to a boil and add mussels and littleneck clams to the boiling water; cook until shells have opened, about 3 minutes.
