If you're thinking that a chunk of your head is missing (yow!) I think your ok.
https://www.amazon.com/GOOFIT-Compl...der+head&qid=1536090313&sr=8-3&ref=mp_s_a_1_3
I do believe that fat part nests down inside there and is supposed to crush down on a gasket.
Looks like your bolts rattled loose and it fell off. Probably need a new gasket. And a couple bolts.