The seashell that I keep scattered on beaches all over the world.
我所收藏的贝壳分散在全世界的海滩???
The seashells that I keep were scattered on the beaches all over the world
或
The seashells that I keep are from beaches all over the world. (这句比较正确)
我所收藏的贝壳来自全世界的海滩。。。