Tiny Fern Found Growing in a Bottle

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Hello I was wondering if you could help I would really like to know what this little fern is. Last year I litter picked a beer bottle from the moat around a medieval manor site next to where I live. I was about to put the bottle in the recycling when I spotted there was something growing in it. At first I thought it was just moss but when I managed to get it out there was a tiny fern too. It survived the removal from the bottle but has remained very small. The longest fond is about 2cm, so it has been quite difficult to photograph. I have looked at the back of the leaves but can’t see any markings and I am sorry the back of the leaf photos aren’t very good.