Steamer / Casserole
Looking at them you will notice the absence of the long handle. They are designed for slow cooking in the oven because they diffuse and hold the heat. The lids keep steam from evaporating and the cooking is completed with moist heat. The moist heat comes from the foods themselves- the juices released from a mirepoix stewing in butter, splash of wine or other liquid that might be added by the Chef.