Hey guys...this isn't an emergency, so mods please move if you feel then need.

I have a rock covered in a thick group of green star polys, and it is looks great, it is spreading to other rocks now. I recently noticed there are a few "trunk" like things coming out of the middle of the group and it is dispensing a stringy slim...any idea what this is?

I have attached a picture of it....if you look at the very top you can see a "trunk" with a string hanging from it...there are a few more in the middle of the rock. Thanks in advance for everyones help.