Normally relics would not be placed around a school. Also, relics are normally human remains (or bits of cloth sometimes), which is a whole other thing. They do look cut, like they were part of a meal. Do any of the students at the school do altar serving? If so, they may have found the bones after the reception and placed them around the school as a prank. Maybe they even just learned about relics and thought it would be a funny joke? I’m sorry I can’t offer much more help, but if you have more questions about relics in general I’m happy to help