Ha, yes, off topic, but fun! Maybe the Sandbox forum needs a water lovers group.
My cactus did have a tag just saying Notocactus. I looked at Parodia oxycostata and don't know if it's the correct one. The info for it said it had 6 to 7 ribs which are very angular. This one has 11 ribs on each one, and they aren't super angular. The coloration also seems like a much darker green on mine, but that could be due to growing conditions.
