One of the so called ball Cacti from southern Brazil reaching up to 20cm tall and 15cm in diameter, more of a stubby sausage shape than a ball if you ask me. Although juvenile plants are much more rounded. Heavily ribbed the spiny and hairy stems will regularly produce pale yellow flowers during a hot summer. Although we have had these survive down to -6c in winter they did suffer a large amount of damage, despite the roots being bone dry, and it took a few years to recover. Best to keep in a pot, moving outside for the summer months and then bringing back under glass in the Autumn. Plant in full sun with a very gritty, sharply drained compost.
Sent as a young plant in a 5cm Pot.
Additional photo by Subhrajyoti07 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=60475868