$2 1940s Atomic Bomb 3D model by nick-a-tondreau. Available on CGTrader with 2 polys. Geometry: Polygon mesh. Check it out on CGHub.
STL (Stereolithography, filesize: 6.77 MB), OBJ (OBJ, filesize: 8.87 MB), DAE (Collada, filesize: 19.3 MB), BLEND (Blender, filesize: 7.23 MB)