This is Asplenium nidus, or Bird's Nest fern; though I'm highly intrigued, I don't have a definitive answer for you. There are two possibilities - either there's some insect, mite or larvae inhabiting the crown of the plant, causing damage to new leaves just before and as they start to grow, or some genetic change has taken place, and these strange leaves are the result. The plant otherwise looks healthy, apart from a couple of browned edges on the mutant leaves. If you've not observed any insect activity at soil level round the plant, then I can only draw the conclusion that this is a genetic issue - these can occur randomly, or are sometimes triggered by damage of some sort (bacterial, fungal, physical, environmental, viral, or hormonal malfunction). It would be very interesting to observe future leaves in regard to whether it continues to produce only mutated leaves, or does produce some more normal leaves. There are varieties of Asplenium with jagged leaves, but they're all jagged, not mixed like yours. I'm sorry I can't be of more help,but perhaps someone else might have a different suggestion/answer.
It's certainly extraordinary, I've never seen anything quite like it, and I've grown this plant myself.