Rattle in my empty gas tank

[MikeIIDC@domain.elided]

Well, the noise that I heard rattling around in my empty gas tank
appears to have been the internal "filter" that I have heard about.  I
had never seen one-even though I had to do this to both tanks on my '68
T'all, but everyone has assured me that there was a filter mounted
within the tank.  Well, while cleaning the tank out, I saw something
floating past the hole for the sending unit as I was power spraying
water through there.  It was tricky to catch it, as I had to be spraying
lots of water in the filler tube to get  it to float by the hole, and if
I missed it, I had to wait for it to randomly-as prodded by the water
gods-show up in hte small hole again.  Then I had to have the speed and
manual dexterity to get my fingers in there and get it before it
disappeared again.  Anyway, got it out and it is a small cylinder with
an opening on one end, apparently for the uptake tube to slide into.  It
look slike a filter, and I don't know what the hell else it would be.
Sound like a filter to you?  Can I get one to replace it?  Is it
absolutely vital?  I have two in line right now; if I leave this one
off, knowing that the tank is very clean and free of debris, will the
other two be enough?
I am thinking that what was happening was that this was getting sucked
up against the gas-to-the-carb tube when the gas was low and it was
running.  There was no gas getting to the first filter immediately
outside of the tank.  Make sense?  Or should I still be looking for
something else?

Thanks!

Michael