Ok, well, I was wondering. So how would it survive without oxygen?
It didn't. What's in the rock are fossilized remains, or at least that's what the scientist claims.
There are many forms of life that do not need oxygen (at least not O2). In fact early Earth life faced a crisis when plant life (consumes C02, makes C and O2) produced so much oxygen (highly corrosive) that it threatened to kill off all life on Earth. Happily animals came into existence and consumed the excess oxygen (and made CO2) that plant life was producing.