What features might non trees but with same ecological functions of trees, take?

What if living "rocks" could constitute a forest similar to stalactites but facing the opposite direction? By rocks, I mean rock-like morphology and being as numerous as rocks.

How might the second gut evolve?

Guts are pretty dexterous and could be made more dexterous. Maybe with microbes for cleaning, in a human gut, the surfaces aren't flat but have stripes that are almost prehensile. If a gut entrance point was larger and wider but still able to grasp as well as clean, it could be a bona fide prehensile organ.