The Enderman can pick up certain blocks and move them around. Creepers can blow holes in the ground. But apart from these, mobs generally cannot affect the terrain.
You can download mobs minecraft comes alive
In Minecraft Classic, mobs can't spawn, so they can't exist naturally. If you play the Survival Test, and when mobs spawn there, you can save it and open it in creative mode so then the mobs can stay there. However, in Minecraft Creative Mode, mobs can spawn, but they can't hurt you because you have no healthbar.
There is lava and mobs, maybe gravel. If you follow the 2 main rules of minecraft which are 1. Never dig straight up. and 2. never dig straight down, you will be pretty much safe.
37
Put it on peaceful
As of Minecraft 1.8 (the 2014 "Bountiful Update"), Java Edition had 39 mobs total, cumulative since the game's start.
Mobs are enemies, so I suppose that there wouldn't have been.
No, mobs will not spawn in water or ontop of half slabs.
40 mobs, up one from 1.8 with the addition of the Shulker (added in 15w31a, part of the Combat Update).
Creepers can not have kids in vanilla Minecraft. No hostile mobs in Minecraft can be bred.
You kill mobs and players
The squid