I was replacing the fuel pump on my mazda millenia and in the prosses i broke a

[jitterbug]

round little plastic part? on top of the fuel pump. Auto zone doesn't sell that part just the fuel pump, and i am having trouble figuring out what that piece is called so that i can try to find someone that does sell it. Theres a big circle piece on top of the fuel pump and in the middle of it there is another smaller like washer type circle that pops off, that is the part i broke. If you know what it might be please let me know