Altar plate? You are probably referring to the patens. They are used to hold the large host and they are used to block the Eucharist crumbs from dropping onto the ground.
Yes the Pacific Plate, North American Plate, Cocos Plate, Nazca Plate, South American Plate, African Plate, Eurasian Plate, Indian Plate, Australian Plate, and Antarctic Plate are the major tectonic...