What kind of insect was it?

My brother told me there was this huge bug that looked like a cockroach in the garage. My mother dusted it out into the front yard and I came to look at it. It wasn't a cockroach at all, I knew that much, but I didn't know what it was. It had yellowish things sticking out on both sides of it's face. It looked like the "horn" on a rhinocerous beetle except yellow, not as thick, and on both sides of the head. It's legs were the same color as the things sticking out of its face and a bit longer than a beetles. It also had a black shell-like thing on it's back. The shell wasn't smooth though. It had smooth, even, sort of wavy ruffles. The thing was on it's back though so I couldn't see all of it and my father decided to squish the poor thing instead of just leave it outside. Sorry for the vague description, but does anyone know what is and if it could harm you?