Finding that the space which opened up was not actually an entrance to the city of the elves was surprising. but , it explained a lot about their society.
"This is the passageway we bring all visitors who have not been verified as acceptable to walk about our homes. We also keep prisoners and other beings within these walls." The captain made it clear that he was explaining this for a reason.
The vines and branches that made up this massive wall used to protect their city were actually hollow. It was a massive explanation of how the city was safer from the attacks and the risks that came with accepting merchants, visitors in general, and stopping beasts that wanted to some within.
Their beasts could use skills that shaped these walls. Therefore, they could trap any attacker or criminal within. It would further allow control over who was coming and going. But when it came to criminals or dangerous beasts, this was a very deadly trap.
Creation is hard, cheer me up!