Don 't add anything you find in your house!!! You can add some gravel that you can get in a bag for under 5 dollars at petco. As well as DO NOT ad the clay skulls. They can release diffent minerals and cotain toxic paint that will harm your beta. Plastic plants look the same as real, and are much much cheaper, plus the betta won't know the difference! Small glass figurenes are okay, but shells might have harmfull debree left in them!