Only hostile mobs spawn, no passive (Or supposedly it does), and it seems that large cave openings happen here a lot.
Dimension
Overworld
First Seen
1.0
MCE made a biome that was going to be at the level of deep ocean, and called it "Dark Forest". But nothing happened, and it still looked like deep ocean, so changed the name to "Underwater Forest" and tried to get trees to generate under the water. Still nothing happened, and when he changed the height level to low plains it generated what you see now. He later changed the name to Death Forest, as it had a dark red color to the biome and many trees allowing darkness and mobs to spawn. The sky color is also a red.
Only the manchineel (man-chi-neel) tree generates here. When walking on the logs or touching the leaves, it will hurt you. However the planks from this wood does not hurt you. Red and brown mushrooms generate, as well as tall grass. But no flowers generate in this biome. Lakes do not generate either. The top block is grass and the filler is dirt, like a normal forest. The color of this biome is a dark red.
Supposedly only hostile mobs spawn here, but that is unknown if that happens. No passive mobs, or even passive cave mobs or squids are suppose to spawn in this biome.