In one of the earlier chapters of JTTW (right before the White Bone Spirit arc), there is a Daoist abbey with a magical ginseng tree with weirdly shaped ginseng fruits. It's said just smelling them lets you live for 360 years and eating them gives you a lifespan of 47 000 years (so basically they work like the peaches of immortality).
So the pilgrims stop there for two chapters, the Daoist disciples there offer Tripitaka a ginseng fruit, but he declines, because it looks way too much like a human baby for his comfort.
So, Sun Wukong gets a mad craving for ginseng fruits, steals some for himself and for Bajie and Wujing, then there is some more shenaniganery, Sun Wukong uproots the tree in a temper tantrum, the Daoists are understandably upset, the pilgrims get in trouble and Guan Yin has to come fix the tree and everything.
So the whole thing ends with everyone reconciling and having a nice party and eating magical ginseng fruit and now Tripitaka finally realises they're in fact not eating babies.
So the thing here is, in the end he agrees to eat a magical ginseng fruit. Which gives him that 47 000 years of life thing. It's also briefly noted that, after eating the fruit, he feels fitter and healthier.
And for some reason ... no one ever brings that up?
Like, from that chapter on, Tripitaka is basically immortal (unless directly killed, I presume).
And it's never mentioned again for some reason?
I just think it's very interesting! There's so much you could do with that tiny but mighty detail!
You recently moved to the countryside. Your child was playing in the woods, and came back with a large green egg you thought was plastic, so you agreed they could keep it if no one claimed it. Your kid said it was a gift. You thought nothing of it. Then the egg hatched.