The word "asteroid" literally means "star-like", because when they were first observed, no telescope could see enough detail to know what they were, so they were basically just called "those things that look a bit like stars".
Even when eventually we figured out what they were, they were generally considered to all be spherical like tiny planets (see: The Little Prince) until the 1970s when one of the Mars probes flew close enough to have a look at one.