Here are some possibilities and what they might refer to:
* Ruminants: This is the most likely possibility. Ruminants are herbivorous mammals that have a four-chambered stomach. They chew their food, swallow it, regurgitate it, and chew it again to extract maximum nutrients. Examples include cows, sheep, goats, and deer.
* Rumination: This refers to the act of chewing cud, which is common in ruminants.
* A fictional term: It's possible "ruminauts" is a fictional term created for a specific purpose, such as a science fiction story or a game.
If you can provide more context about where you encountered the word "ruminauts," I might be able to give you a more specific answer.