Rocks can be classified based on texture. The size of the grains in a rock affects its texture. Coarse-grained rocks have large grains, and fine-grained rocks have small grains. Rocks formed from magma under Earth’s surface have larger grains than rocks formed from lava on Earth’s surface. This is because magma cools slower underneath the ground than it does above ground. What kind of rock is this? Where would this rock most likely be formed? To which group of rocks would this rock belong?