In the same time it took to wear the middle ring this is the same damage to granny.
It's actually not so bad (well, compared to middle), even though I do try and spread the wear by switching to granny gear whenever possible (I don't like standing to climb).
The new silver one behind is steel. The bike originally came with a steel granny but on the first replacement thought I'd try the alloy (that's in front and black). Anyhow, going back to steel here to make it last longer (oh, and will defo keep an better eye on the chain now too - after two full drive train replacements have learnt the lesson!).