Removing bathroom faucet aerator
I'm still not sure what kind of aerator this is but I was able to remove it.

After keeping the tip of the faucet soaked in a small bag of vinegar for a couple of hours, I was able to turn the aerator with a screwdriver but it didn't really feel like it was coming out. The plastic was also brittle and started breaking apart when I tried turning it, so eventually it came out when it broke apart. It looks like this is simply a plug since there appears to be no threading in the faucet.



I'm going to have to see if I can find some kind of replacement for this that will fit in an unthreaded faucet.