A misread lead me to think about proverbs/sayings in Eridian.
I have encountered one example in fanfiction so far, "You use three hands to eat" being a strong insult, from Astrobiology immersion program (https://archiveofourown.org/works/82728511), and "lover of life itself" being a phrase for aroace (don't remember where).
There can be "Flip over!" as a "fuck off", partially because eating in Eridians is obscene by the books, partially because that's a bad position.
I wonder if rough or smooth textures are considered more pretty? What would sound better, a highly conductive materia or a pillow? Or is it a layering thing? Would "you blend in with xenonite" be an insult, a weird statement, or a praise? Similarly, metal has a similar reflectivity compared to water (there are bat studies about those). Would little metal beads be a pretty thing? "You echo like the ocean" can certainly be a compliment.
And yes, by the book, there are oceans on Erid. Haven't watched the movie yet, but they were involved in astrophage production for Blip-A.
Different stones of the carapace can be associated with different properties, too. Both on carapaces and as a material. "Sharp like quartz" comes to mind, that is, if eridians associate smartness with sharpness, and even then it can be used in other contexts. Or there can be "smooth/soft like talc" as a description of clothing. I wonder if it's commonly made of asbestos (rock wool) or palygorskite (mountain leather).
"Hotter than an active volcano" is definitely a phrase, maybe as well as "freezing sulfur/iodine" (they have freezing points at around 110-120°C in this pressure [I did check phase diagrams], which is a reasonable point to be very cold considering 210°C being the room temperature; I'm not sure if there will be any free iodine, though), and maybe also "colder than astrophage/biodome" as a newer opposite.
Patchy colours of the Blip-A and the cylinders could be because of crystal grain. And we can discern grain size and packing with basically echo. "Grainy" can be synonymous or related as a word with "shoddy", because fault lines in materials lay between grains most of the time. Answering my earlier question, this might mean that sound-absorbing materials would likely be considered less beautiful, and pumice to be particularly ugly. That can open up doors to insults, like "can't hear a pumice from a quartz/limestone".
"Thrumming by themselves", for oddballs and loners, lost in thoughts.
"Discordant/accordant note" for something/one not fitting -- or fitting. Also a "missing cord", obvious one, too.
Although, for more fun phrases I'd have to speculate about culture and nature (what do Eridians eat as apex predators?). Not at this hour, I think.