Final answer:
Archaea is the domain of organisms that thrive in hydrogen sulfide caves, forming snot-like colonies.
Step-by-step explanation:
The domain of organisms that thrive, forming snot-like colonies, in the toxic-to-humans hydrogen sulfide caves is Archaea.
Archaea are single-celled microorganisms that can survive extreme environments, including hydrogen sulfide caves. They have a unique cell structure and biochemistry that allows them to thrive in such harsh conditions.
Examples of archaea that form snot-like colonies in hydrogen sulfide caves include organisms from the genera Thiothrix and Thiovulum.