That is a Koralia Hydor powerhead. Hydor is the line made for nano tanks. I'm not sure what that first piece is, looks like a washer or a nut. In terms of the piece you broke, you might be able to glue it back on, just make sure you use a glue that is 100% cyanoacrylate so you don't leach anything nasty into your tank. No clue if it'll hold since that looks like you broke one of the snaps that holds the 2 pieces together on the powerhead.