need to flip/rotate an object in in a strange way

Hello. I am working on wall-e (modeling) and am working off a maya tut.
Please see attachment.
Now I created the left eye with out a mirrior and then when I done a duplicated it and moved it to the right side, somehow I need to flip it and there is some kind of way to flip or rotate to the position that it needs to line up with the background on the right side. It is a simple procedure and have done it before but just don’t remember how it’s done. Not very good at explaining it all but hopefully you can look at my attachment and see what I need done
Thankyou for you time and effort.

Try to scale it by negative 1 on the axis you want tot mirror it on.
(press s, the axis, -1, enter) <- just in case…

Why don’t you just mirror the entire left eye?

Thankyou both very much.
@Lommbard. what you said to do worked perfect.
@blenderallday. I tried the mirror modifier and I couldn’t separate the objects but this was in object mode but I tried again but in edit mode and was able to separate the objects. So I am going to keep the mirror modifier.
Thanks to both of you.