So, these acrylic containers are seen in Phlox’s Sickbay and I subsequently found out that they were made years earlier, supposedly for TNG. This image is from the Makeup Effect Laboratory website and it shows lots of them, with what they describe as organs inside them.
I can’t figure out what episode they would have been commissioned for. MEL says they worked on TNG from season 3, so that might be a guide. The earliest example I can find is from TNG 4x23 The Host, where I only see one used and the Trill worm is obviously not like the organs seen in the MEL photo.
I’m betting it’s something obvious that has slipped my mind. But, it could also be something originally made for another show and repurposed for Star Trek.