Because the gravity of the worldlet within the Teruvar is artificial spin gravity, as one moves toward the central spire, gravity becomes less and less, though the air pressure is constant. The back wall of the Teruvar, opposite the clear membrane, and from which the spike protrudes, is covered in vegetation, with strange zero and low gravity creatures abounding. The rim, on the other hand, is home to more normal ceatures, who walk about, rather than brachiating or flying or crawling through the vegetation.
The amount of spin gravity depends on the diameter of the Teruvar and the speed of the spin. Since even the smallest Teruvar is many tens of kilometers across, the coriolis effect at the rim is seldom great enough to be noted. As one ascends the back wall, of course, the diameter becomes smaller and thus the coriolis effect becomes more and more powerful, and may become difficult. The variation at the rim is a continuum between a third of a G in the smallest and something over a G in the largest. In the seven Teruvar accessible to Humans and Jeshen, all fairly large, the variation is between 0.77 and 1.05 G, all perfectly healthy for both species. This is probably not coincidence.
Generally, the central spire glows from reflected sunlight at a level uncomfortable to look directly at, though it will not permanently blind. Light levels inside are lower than a sunny day on planet, more like a cloudy day, and the source is far more diffuse, but there is plenty of light to power photosynthesis. The rapid light changes that occur when Teruvar are communicating can be disconcerting. Most inhabitants close their eyes when this is happening, standing or sitting still until the communication is over.
Water circulation within the Teruvar is constant. The water is pumped up the back wall through tubes, and out into the central spire, from which it falls periodically as rain. There is some purposeful leakage along the back wall, surfacing as springs. The total amount of water in the Teruvar is determined by the amount of ice in the original asteroid or moon, plus whatever ice the outer surface captures.
Scientific opinion is divided on whether the changes over time in the flora and fauna of the interior are controlled by the Teruvar to some extent, or are entirely driven by natural and sexual selection. Some in the "Control" party suggest the seven Teruvar open to Jeshen and Humans are experiments of the Teruvar as a whole, so they may create their own sapient animals by copying what they like.