River Dome

River Domes are a strange plant species that are found in rivers. They start off small, looking like brown rocks with leaves on top, but grow to be much larger. They seem to be relatives of trees, as they are covered in bark and eventually grow large leaves somewhat similar to palm trees. They also have layers, as can be seen with a cross section of a mature Dome. The most peculiar part of this plant, however, is that the inner layers die once they are sufficiently covered. While more layers continue to grow, the inner ones begin to rot and get carried away in the current. This creates a space inside which certain creatures use as their homes.
The wood from River Domes is not a very good building tool, due to the shape and the fact that it naturally crumbles within about 5 years. Certain preservatives can stop the crumbling effect, but they are still only the right shape for bowls and a few other niche implementations. They also don’t usually get large enough for humans to live in. However, the real value comes from the unique organisms that can be found underneath the domes.
Underneath a river dome is dark, damp, and protected from the outside, as well as having a floor of fresh water. This unique combination of traits means there are certain unique organisms that can only make their homes there. For the most part, they are small harmless, and rely on the river domes for protection. Children from Zenne like to play with and collect these cute organisms, and sometimes bring them home. River domes can grow anywhere with running water, and since a lot of houses in Zenne are situated along the river, it is common for kids to grow their own river domes and fill them with interesting creatures.