What is coming out of my pipe and how can I fix it?
It looks like the tee in that spot is in need of repair. It likely wasn't sweated (soldered) properly.

If you don't fix it, it will likely continue to grow. So in a sense, it is alive...

EDIT: I was wrong in an earlier version of this answer where I said that copper oxide is blue: it's actually black. The blue/green that you see may be due to minerals in the water, like sulfates, which react with the copper. Others mentioned in the comments to your question that it may be due to the acid flux that was originally used when sweating the joint. A flux like that has HCl and have salts that can react with copper to form copper chloride, which is green.