How to break up one mesh into submeshes by connected vertices?

I been trying to figure this out for a while. I have a mesh that is made out of multiple extrusions. It is an FBX object when I import i would like to separate certain triangles to create a submesh of each continous mesh within the FBX object.

Now I understand how to make submeshes, but What I am trying to figure out is how can I check if triangles are connected through vertices that share the same position.

The ideal solution would be to cycle through all vertices check if they are part of a sequence of connected vertices and compose a list of triangles to create that submesh. When the sequence of vertices are broken i would like to start a new list for the next submesh until there are no more verticies to cycle through.

The object is imported from another 3D program that doesnt export the meshes separately.

I know this would be super easy in any other 3D program, but trying to stay within Unity.

Thanks in advance!