This is the female with shell of an alien race for my personal project. The male is drastically different so I'm still working on it. I've got a lot of artwork for this project in the works and hopefully I'll be able to start posting a finished one every week or every other week for a couple months.
Basically. It's a case of exosymbiosis where the alien starts off small with some of the exoskeleton covering it. The exoskeleton grows faster than the alien and also stunts the growth of the alien so eventually the alien is sort of pushed into an extremity like seen here. For younger ones, it's more like armor than a host.
Ah, so kind of like a partial attachment at first, then it just grows and grows until the alien more or less lives within the bigger things like a living exosuit of sorts?