I've been trying recently the Minecraft mod pack Technic using the Technic launcher. It's set to "always use recommended builds".
After spending an extended stay underground oogling all the shiny new gemstones and such, I came back up to the surface and did what any minecrafter would do. I built a floating marble brick house over the ocean.
All was fine and dandy until I went to collect some sugar cane. I came back to find my house contained a pack of about six turtles! Considering I had left my front door open, I gave them the benefit of the doubt... and shoved them out a hole in the wall into the ocean below. (Turtles can swim, right?)
After making sure to close my doors this time, I went back out to harvest some rubber. After breaking my treetap and returning, I found my work area filled by several snakes! Unacceptable! I built myself a sword and now am the owner of a few snake eggs.
Why does this keep happening? Why do I find various wildlife creatures to have spawned inside my home?
My house is well lit by torches, if that matters. I also play on peaceful 'cause caves noises scare me quite enough, let alone creepers.