Not just roots, how about earthworms. They love to get into my pots and do so even though my pots generally are on slated wood platforms that raise the pots 2" off the ground. I cannot tell you how many times I have un-potted a fiddle leaf or banana leaf ficus to prepare for shipping, and low and behold, there is a large earthworm happily living there. I am careful to look for them after the episode with the lady in New York City. Of course, if I could have it my way, I would love to have my potted plants as homes for earthworms.