Originally Posted by 5picker
Without the proper tool... I would find a bolt with a head the same size as the plastic hex.
Insert the bolt (head down) into the plastic hex and clamp a pair of vice grips to the threaded end of the bolt and turn apart.
This worked perfectly! I feel a little silly for not thinking of it myself since a number of "special tools" I have at work use this method with two nuts so you can put a wrench on it.
The aerator does have a black washer on it, and a spring in there for some odd reason. After getting disassembled and cleaned I'm still getting awful water pressure there so back to tracing the water line back.