Nice find! It is sad the dating letters are weak/off flan but I suspect ID would be possible with some work. Marcus Aurelius was around for many years and aged as we watch on coins. The style will help pin down the ID.
Amazing. As I've previously mentioned, I saw a Marcus Aurelius sestertius found by a colleague in the field on my first day detecting in the UK. But it was nowhere near that nice. What a thrill that must have been!