Bingowings said:
Thanks Tobar, it looks more like just a mouth in a pit (a bit like the OUT Sarlacc only really big).

Lucas asked Archie Goodwin to not show the slug's body coming out of the case, in order to preserve the visual surprise for those reading the comic adaptation who had not seen the film yet. If I remember correctly, the first couple of issues of the 6-issue adaptation were in circulation prior to the film's release date. Especially for those who had comic subscriptions (ahh, the days of anticipation of getting a new comic in my mailbox!), we were reading comics a month or so before they hit the comic racks in stores....