oceanic crust
rocky almost cement crust like granite found in continental crust and basalt found in oceanic crust
A rift valley is formed when tectonic plates move apart, creating a gap in the Earth's crust. This process is often associated with divergent boundaries where new crust is formed as magma rises to fill the gap. Rift valleys can be found on land or under the ocean.
No fish live under the bottom of the ocean
Salt water
Any rock can be found in the ocean because of erosion (except dry ones).
a organ of a blue whale, all kind of plastic and dead animals
The only answer I can think of is Starfish.
Dry stones
Only if some Norwegian in a boat throws it overboard (kind of like "can tuna salad be found in the Pacific Ocean").
Most basalt is found in the oceanic plates. Most granite is found in the continental plates.
Sea floor spreading is primarily found along divergent boundaries, where tectonic plates move away from each other. As the plates separate, magma rises from the mantle to create new oceanic crust at the mid-ocean ridges. This process contributes to the continuous expansion of the ocean basins.
The oceanic crust is formed at mid Atlantic ridge.A chain of under water mountain range with active volcanic activities pushes apart the new ocenic crust.Note that if ocean floor is created then it is also consumed else where at a subduction zone situated in Pacific Ocean so called ring of fire.Otherwise the volume of earth would go on increasing.