I dunno what substance is in there, but it's visible when you glance down. I'd take a pic but it turns my stomach a bit and would have to put a warning on it
Anyhow, its a 6-spoke metal drain cover that can't be removed, no screw, so i have to work through it.
What do you guys do with trouble drains? I wish i could just spray a load of foam in there and rinse the problem away.
I'll get a pic later
PS i dont think theres any trouble further down the pipe, its just something's built up nearer where you can see it.