When II tried to hit cobble stone with my iron pickaxe in a branch it took a little more time than a normal cobblestone block to destroy. It was cobblestone only, I collected it when it dropped. But when I mined it it broke but some rat-like thing came out and crawled towards me and hit me. It did not do any harm, I killed it. I was digging in a 3 block high pathway when this happened. It happened in the whole column of 3 blocks. I saved and quit the game and posted this question. What it this? What does it mean? Have you faced this? Please tell. I am not using any mods. Beta version.