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.
By definition, organic sediments are those sediments derived from the disintegration / decomposition of plants and animals. Their origin might have been in swampy places (but not necessarily) in past but now they were transformed into sedimentary rocks mainly under the weight and pressure of overweighing rocks.