Clay rock stone decorative n1 (Polygon mesh 3D model) is available on CGTrader for $5. Original author: 3d-vlad. Specs: 310000 polys, 170000 verts.
OBJ (OBJ, filesize: 68.2 MB), MAX (Autodesk 3ds Max, filesize: 136 MB), FBX (Autodesk FBX, filesize: 68.2 MB), 3DS (3D Studio, filesize: 68.2 MB)