Pretty positive the answer is shapes
Earth's crust is made up of huge slabs called plates. The plates move constantly. At times, the plates move away from each other, creating gaps. Earth's surfaces finds it's way out of the gaps. Magma comes out of Earth, creating a heap of lava, ash, and rocks. The heaps grows bigger and bigger as the volcano erupts and, creating q huge mound. The mound cools down over thousands over years to form a mountain.
Because if a cactus didn't have needles a lot of animals wouldn't get poked and they'd eat it
