The Mother of All Table Arms

Sartagua can swallow a target within five meters and you don't immediately die. He regenerates like 30 hit points around. What else is in there that's going to like grab you? There may be other things living inside there like gut bacteria, but bigger and with tentacles. The mother of all table arms. You say that I'm having flashbacks to cold fire within when we got eaten by a dol and the other creatures we found in its intestinal tract. We even learned spells from that little guy in there. But apart from making these creatures manifest from the pages of our books, how might we use Sartagua or his formless born in our games?