The porcelain layer is attached to the metal and makes the crown look like a regular tooth. In comparison, the all-porcelain or all-ceramic crown does not have the layer of metal as part of the crown. The porcelain itself is what goes onto your tooth.
Quick Answer. An abyssal plain is a deep undersea area created by sediments overlaying a rocky crust, and they are the flattest places on Earth. Abyssal plains cover one-third of the Earth's surface, as much as all land above water, and they sit near continental borders and underwater mountain ranges.
Flat area on a deep ocean floor, located between the foot of a continental rise and a mid-ocean ridge, usually at depths between 3000 and 6000 m. These plains cover more than 50% of the Earth. ABYSSAL PLAIN: Abyssal plain are the least explored regions on Earth..