Important: G-B-Shrooms-Rocks.mat has multiple layers of ecosystem, and the grass layer is dependent on the tree layer. To populate, start with the rock (Default) layer–that’s your foundation. Then populate the Bushes layer. Then populate the Trees, and then last, the grass. The grass will be more dense around the trees. Note: The Rocks layer didn’t want to save the name in the mat, despite repeated tries. It is instead still named Default layer.