Radioactive Goop

Appearance:

Radioactive goop looks like normal goop, but a lighter green colour, and with a distinct green glow coming from the goop.

Behavior:

Radioactive goop almost never stops being radioactive, and only has when close to other goops, although, it does seem to get more radioactive the more danger it senses. It's radiation can immediately kill, and even change the appearance of living things at it's will.