Hello All
Ocean crust is less dense and thinner than continental crust. The age of oceanic plates are only a few hundred million years compared to several billion for the continental plates.
Take as an example Pacific plates Hawaii. The crust forms a convection wave cycle that moves towards Japan into an oceanic trench, the wave crust continues meets the mantle and through friction mantle and crust pops up again on a hot spot called Hawaii.
The lava show evidence of fossil properties of the surface crust.
Smile and live another day
