When replacing my rear brakes I'd obviously took the engine cover off to make sure I could monitor the brake fluid level when rewinding the calipers and spotted the below...

 

   

 

 

Could it be the remains of my turbo popping episode back in January?

 

It's nothing to worry about, mines been like that for ages, so have 90% of the ones I've seen. Most just opt for an egr delete

Ah, is this the infamous EGR valve then?

It's either the seal between the boost pipe and the egr or the rubber seal between the inlet manifold and egr. Failing that I believe some egr valves tend to leak which surely can't be a good thing.