Deid bodies under the floorboards most likely.Theirs a guy in my town who has venomous snakes, (cobra and Tai-pan) he lives a couple of doors from my mate, just a normal ex council house. We have a Tortoise, was speaking to the guy in the exotic pet shop about him, apparently the snakes are in double locked vivariums, and the floor has alarmed pressure pads. Three monthly visits from the council to make sure everything is working to ensure he can keep his dangerous animals licence.