Yeah that weird little part is part of the mesh. It was pretty challenging for me to try and make it as accurate as I could. Lots of trial and error for me lol. But its pretty much just breaking it down to its simple shapes and planning out how many vertices will be needed for everything to connect properly. For the purposes of a game asset pipeline, it would not be necessary to model it as one mesh as there are baking tricks to give the illusion that it is smoothly integrated even though its modeled separately.