What is this, and is it important?

[dcalnan]

was getting my co2 system ready for keeping and put on the regulator and no co2 was coming through. So upon investigation I discovered this gold coloured disc sitting in the middle of the connection part to the tank. So i said I'd try taking it out, and low and behold it worked. So my question is what is it and is it somehow important. It looks like it's composed of tiny little gold balls. But it's definitely blocking the co2 whatever it is.

[Eugene O'Brien]

http://www.alliedfilters.com/sintered-metal-filters.htm
Scintered metal filter. I think it may stop liquid from coming through. Maybe.