What is that?

This strange thing (I suppose it's some kind of moss) caught my eye when I visited my relatives in the countryside. It resembled tiny palm-trees!
I was in a hurry, so I took a couple of photos hoping I would be able to take more next time, but next time this thing was already gone...
I would really appreciate if anyone could tell me what this thing is
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I've found out, it's Marchantia polymorpha