11. If the Washington Monument had regular faces, it would be an elongated square pyramid . 12. The square pyramid , with square base and four triangular outer surfaces, is a common version. 13. He finds the volume of rectangular prisms, pyramids, and the frustum of a square pyramid . 14. The elongated triangular pyramid can form a tessellation of space with square pyramids and / or octahedra. 15. Already this simple square pyramid shows that the symmetry-accumulated incidence matrices are no longer symmetrical. 16. The gyroelongated square pyramid is a square pyramid with a square antiprism connected to the square base. 17. The gyroelongated square pyramid is a square pyramid with a square antiprism connected to the square base. 18. This partitions the cube into 6 equal square pyramids of base area 1 and height 1 / 2. 19. A thatched roof mosque with a square pyramid or double pyramid mosque forms the centre of the village. 20. A two-seater weatherboard outhouse has a square pyramid roof of corrugated iron with a wood finial.