Dwarf Citrus Water Shoot
It is definitely a sprout. Why it formed is hard to say. I suggest that you let it grow for awhile and see what happens. It may get thorns on it.
Thanks for that Mike - appreciate it. So are you saying if it get thorns, keep it. If not, lop it off? Cheers. Ted
It depends on why you have the plant. If it was mine I would be growing it as an ornamental plant and out of curiosity. Many citrus plants (plants in the Rutaceae family) are covered with long, sharp thorns. I doubt if yours will be because the shoot would have had thorns from the beginning, but I would wait awhile to find out. Once your curiosity is satisfied you can cut it off.