Glassland

Glassland actually was in a different mod MCE worked on a long time ago. It was called the "RFT Mod", meaning "Requested From Twitter" where people would send in ideas through twitter to suggest things to put in the mod. However, this didn't really happen and he deleted the mod. The glass biome was in this mod, and actually had a mob called the Glassman, which was like the Enderman. The Glassman might be added back in.

Generations
Similar to what was done in the RFT mod, the biome generates with glass as the top block, and stone as the filler. You can see dirt and some ores, usually coal, because of the glass top block.

Glass trees generate in this biome. The biome uses normal glass, not a new one that it adds in, though that was done to test for generating trees in this biome. The glass tree only generates on glass, no other block.

No mobs spawn, nor to grass or flowers. The Glassman however, might be added in.