I can at least answer the "who did this" question -- in the generic. When a tree is cut down, it leaves a very large stump behind. Now, if you want to remove the stump, that requires a backhoe, tractors, and a lot of effort. (Or termites and time, but that's not a predictable solution.) Instead, you can leave part of the original trunk -- where you cut it depends on the damage / insect activity causing you to cut the tree down in the first place. Then you hire a service to come out, usually with chainsaws, to transform what is left into a work of art. Our neighbor has a family of bears climbing up a dead tree trunk. :-) It's about the same cost as stump removal (cheaper if you're talking about that GIANT stump that the mushroom house is on) and adds beauty and whimsy.