https://bugguide.net/node/view/397547

It only measures around 5 mm when enrolled. I didn't know that beetles had an analogue to the Armadillidiidae isopods and Oniscomorpha millipedes. It's not surprising though - the ability to roll into an armored ball must be a reasonably effective defense in nature, and it can be found in various other animal groups too, even mammals -
https://www.youtube.com/watch?v=-x71UlnYVEU