A question was posed earlier about whether there is wildlife to be found in Lone Spelunker.
The answer is yes. As the previous post might have suggested, for example, sometimes when you enter a cave, there are birds flying around the twilight area of the cave.
Here's a selfie I took upon entering a cave today - you can see several swallows flitting around the area nearby.
Since these aren't considered a "discovery", they don't count as a "trove" in the game, but other forms of rare, surprising, and interesting wildlife found deeper in the caves do. One of the goals of the game is to find locations that will be of interest to scientists, and that includes biologists as well as geologists, so cave flora and fauna play a large role in the game.