Mesh collider information

If i have an object formed by 80 different object and i have to use the mesh collider on it, what i have to do ?
I have to put the meshh collider in each sub-objects or i can put one mesh for all objects?
Thank you

You can either use one big mesh collider or you can use many primitive colliders which together is called a compound collider.

See Bunny’s comment below for more info.