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Are comets made of sulfur?
Get real.
The above talks about sulfur being released from planetary strikes. Both in the form of sulfur from the object, and the object hitting rocks that have sulfur.
I'd be interested in seeing some of the photos you mentioned from the air. I did a quick search and didn't see anything. The movie you linked to previously, the structures might look like buildings, but pretty sure they are just natural rock formations.
And while God can use any mechanism He wishes for a miracle to happen - I think He often uses “natural” phenomena which He can control if He so desires.
Could be some have a lot of sulfur in them.
"Oxygen and sulfur are the third and tenth most abundant elements in the solar system. The isotope ratios of these elements are different whether found on Earth or a meteorite.