fern died in my care before I could identify it

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Hello. I sometimes grow fern from spores as a hobby. A friend once sent me spores from the US East Coast, out of which grew Christmas Fern, but in one of those pots also grew another fern I couldn’t identify. When a friend tried to separate them, the unidentified fern died, so I only have a couple photos. I’d really like to know what fern that was, so if, despite the lacking source material, somebody could give me any hints here, I’d be very glad. I got more photos of the likes as those that I uploaded but also in higher resolution. I assume that this fern either came with the Christmas Fern spores, or it’s here locally from central Europe and found its way into the pot by chance.
Thank you for your time.