Worked on a 1999 626 mazda 4 cyl and it was leaking oil from the back of the car..?

[Tommyboy619]

Worked on the above the other day and noticed an oil leak under the apron section under he spare tyre. It was oil, not brake fluid. It had a plastic cover with vents in it, so I unbolted it and found what looked like a shiny box under the spare tyre apron. Is this some sort of oil catch canister? Why is it soo far from the motor if so? Never seen anything like it before, thats why im posting. Thanks.