Seer says: "Something stirs in a pool of slimy green liquid. It's ... not human. It doesn't appear to be an animal either. What is this creature?" Who is that and where do I find it?
I'm not sure either, but the top of the Science Lab has a slimy green pool you can try and fish something out of. If you have Linda with you she objects, but afterwards, without her, you can try and fish whatever it is out. Need pretty high senses to pull it out - at 10 senses I had like 11% chance to pull it out.