The same thing happened to my parents a year or two ago. The roots were growing under the house and up through the toilet pipes.
I'm sure most of you have heard of all the Boa Constrictors that are loose and flourishing in the Everglades of Florida. Well I believe that is what I am seeing coming out of that hole in the floor.
Redwood, it's probably about 24 feet long all together. Good thing it's DEAD!