It was plastic. If you go under you will see it clipped on with a weird clip that you have to pull apart to remove. I didn't touch the radiator hoses which is why I got scared when coolant came out. The plastic part is very hard to move out of the way. I finally managed to push it down with a lot of force but I didn't realize that it had some flexibility to it.
Also I don't trust dealers. Took my 06 impala in for a recall and they "mixed my car up with another impala" and drained my oil. They refilled it and didn't tighten the drain bolt so I developed an engine knock. My dad was a gm mechanic so I learned a lot growing up. Smart to do it myself? Probably not. Fun? Yes.