As @usr noted in comments closures are just normal classes, they doesn't exist distinctly in IL. Only difference is you've not created it; compiler did it for you.
I believe you should be looking at unique compiler generated names to find them. EricLippert describes naming conventions followed by compiler here, Do note that it is subject to change in future versions of compiler.
Also after coming to the conclusion that the Type
is a closure you can verify that using CompilerGenerated
attribute.