Forum:Where are all the pearls at?

So I've killed crawmerax online and by myself many times, i've met people online (ps3) and I have received cool mod weapons from some people. But my goal is to get a fricken pearlescent! I can't find one anywhere where there says they drop, I have a gazzillion yellow/orange weapo ns, but I r eally want a tsunami smg. I have a siren, and she's level 69 from the new patch. Anyway, I want to collect weapons. But it seems like I'm not doing a very good job