Answer:
Archaea.
Explanation:
Three major domains of life are prokarya, eukarya and archae. These three domains show different characteristics with each other. Archae are more closer to eukaryotes then prokaryotes.
The microbe that has been discovered lives in an extreme environment is archae because archae bacteria are found in extreme conditions. These archae does not have a nucleus and no pepetidoglycan layer is present in archae. The membrane lipids of archae are different from the peptidoglycan. Hence, the discovered microne shows characeristics similar to archae.
Thus, the answer is archae.