I know. It staggers me.

My youngest son (almost 14), was recently sent something of this kind by a classmate (not a friend of his, I hasten to add) in a school group chat. He immediately told us (because he is sensible) and we alerted the school. He felt absolutely disgusted by what this classmate had done, and also rather mortified (he's autistic, and absolutely loathes incidents of this kind), but I can imagine that's nothing compared with what that poor girl went through.

The school subsequently did a thorough investigation into the perpetrators. They're pretty hot on this sort of thing at my son's school. Progress I suppose, but of course they can only act if things come to light.