I think it's some kind of baked-on porcelain coating.
Never really had one of these things before, but I've read, the anode
should be inspected every 6 to 12 months. I think this one might be magnesium.?.
I saw some pics of anodes that looked half eaten.
I want to pull this one out for a peek and put it back in with Teflon tape.
(So I can do inspections later on).
I'm going to look at wiring the elements to use about 1.2kw at 120vac.
Just in case the A7 needs a little help..