Got pretty lucky on my first day in my new world on Minecraft. I started burrowing to begin building my underground house when I found a cave. It had two routes, one left and one right. I took the left. I traveled for maybe 20 seconds down this cavern and I came across maybe 6 zombies. Luckily I had my sword and some food on me so I killed them all and continued on... Eventually it lead to a dead end, so I started backwards towards my base. I then continued to take the right path and right away I was greeted by yet another zombie. So I killed it. Then another appeared. Unusual amount of zombies down here. Then I came across a mob spawner. It obviously spawned zombies and there were obviously chests with it but I decided to dig a little pit so the zombies couldn't get out. Now I'm going to build my base down here with my own zombie spawner in it.