Accidental oak tree

I seem to have accidently grown an oak tree.  I have no idea how an acorn got into this pot, perhaps one of the girls.  Anyway, I now feel responsible to keep it alive!

Worked late tonight because 1) I am very busy before going on annual leave next week and 2) I forgot it was month end.  I usually do my hours as I please throughout the week but always get caught out by month end as I have to do my time sheet today and I was behind on hours.