How to Ungroup (UnJoin) a Mesh I Need to know how to Ungroup Meshes that were Previously joined Without Undoing History. 

I Am attempting to ungroup things like these.
If you select anything on the models in there you will notice they are a big mesh made with the CTRL J Trick

I Need to know how to Ungroup it from that.

(Unless it can't be done. -_- and i have to try to recreate the meshes entirely)
Select your mesh
Enter edit mode
Select all vertices using ctrl+A
Select mesh menu->Vertices->Separate->by loose parts or just Press P and choose by Loose Parts


This will separate your mesh into different meshes again.