The Tuxedo Urchin normally will roam, several of them could be housed in the same tank if it is large enough to provide them with adequate algae and shelter.
It is sensitive to high levels of copper and it will not tolerate high levels of nitrate either. If it starts to lose some spines, it is often due to poor water conditions.
During the day, it will hide among the rocks, in crevices, or under plants in a sandy substrate. At night, it will emerge to graze on the algae present in or near its home.