Check out Realistic Granite Rock 02-250609 Low-poly 3D model on CGTrader for $9. High-quality mesh by mega-3d: 5000 polys, 2500 vertices. PBR, Textured, UV Mapped.
OBJ (OBJ, filesize: 261 MB), FBX (Autodesk FBX, filesize: 130 MB), JPG (JPG, filesize: 130 MB), TEXTURES (Textures, filesize: 130 MB)