Archebacteria is a good example of an unrelated class of life.
It has a sulfur electron transport system, instead of oxygen, and is therefore unrelated to all life with an oxygen based electron transport system.
This bacteria lives at deep ocean volcanic vents. I studied it for a bit.
Are anoxyic bacteria that don't use oxygen at all (and find it quite toxic) unrelated at all to aerobic bacteria? Not according to anybody I have ever read on the subject.
Citation please, and can you address the universal DNA code and variants of the same ubiquitous “housekeeping” genes that are present with variation in ALL living species found upon the Earth?