An animal I didn't see took the acorn that it buried in my 5th floor balcony flower pot in October

This is a followup of: https://sh.itjust.works/post/48867881

Photo description: The acorn is missing now in the hole the animal made in the remnants of the Edelweiss that died last year in the flower pot with red houseleek and some grass coming out. The grass has flowers now and the housleek grew bigger, as the winter is over.