insignia coolant leak

Afternoon, New to the forum, so Hi all. I bought a 2009 insignia in November which has been running fine and still is, but it has developed a random/intermittent coolant leak. I noticed it and had a google, figured it was the EGR cooler, so rang my local Opel Dealer - had it in stock , would...

I've managed to track down a coolant leak on a 2.0 disel Insignia, it appears to be coming from a tiny crack in a ribbed plastic object, bolted to the cylinder head and located just to the right of the exhaust manifold - photo attached. Can anyone identify this component please? Many thanks.