Trolls were made in mockery of the Ents. They were created out of stone and would turn to solid stone when exposed to sunlight. There are a few physical descriptions on trolls in LOTR, but I ended up taking a bit more of my own direction with them. The main thing I wanted to convey is that trolls were brutishly big, strong and dangerous. Besides that, I wanted the trolls to actually look like stone/rock creatures to really contrast them from the Ents.