Leaking Shower Drain

Replacing Oakum Packing

I found a leak in our first floor shower drain between the PVC drain and the brass drain fitting in the fiberglass unit.

I cut out a gasket in the top of the drain - definitely the source of the leak - and found that the space between the shower's brass drain and the pvc waste line (probably 1/4" all the way around) was packed with what I've figured is oakum.

Any suggestions for refilling that void, thereby eliminating the leak?

Here's a pic of the current status

Put a larger pan/tray under it until you buy your new shower.

what is this???

I guess that's one option...

So here's the latest. I scraped out what seems like an old gasket around the top of the pvc, and underneath it - between the pvc and the brass - was a ton of fibrous material that was packed into that space. I dug as much as I could of it out of there (you can now see the void between pvc and brass).

here's a pic of what I found - it was surprising, to say the least.

First - what the heck is the material I pulled out of there?

Second - can I fill that area with silicone to seal it up?