Biology
There is little to eat, and animal populations are very small compared to the surface.
Swallows live in spit nest colonies like wasps.
Ecology
Cave environments are constant: dark, consistent temperature, and high humidity.
Occasional floods wash leaves, twigs, and plant debris into caves. Some animals who only sleep or raise young in caves will leave some droppings in. Bat and cricket droppings are a major food source.
(https://www.nps.gov/ozar/learn/education/cave-biology.htm)
CAVE
Computer Augmented Virtual Environment, basically a small room with 3D projections on the walls at DisneyQuest.
(The Art of Game Design: A Book of Lenses by Jesse Schell, Carnegie Mellon University, 2008. Page 49)
The Elder Scrolls Morrowind
- Addamasartus