Answer:
aquifer
Explanation:
Most aquifers contain water saturated layers of rock or loose sediment. Aquifers have within them water- filled caves.
Economy, War/Peace with other countries, Importations and Exportations
Euroupean enviorment agency
Cross sections perpendicular to the base and through the vertex will be triangles. Below, you can see a plane cutting through the pyramid, part of the pyramid removed, and the cross section. You could also take a slice parallel to the base. Cross sections parallel to the base will be hexagons.