Classic studs

Classic studs were round studs that existed on Roblox until they were replaced by square studs.

In April 2009, Roblox changed the shape of the studs to avoid potential copyright issues with Lego, since their bricks contained circle studs as well. At the time, many players disliked this change and uploaded models, scripts, and decals to protest. Many popular games use classic studs today, like Natural Disaster Survival.