The jingly celebration outfit that Rocky wore was probably Extremely Slutty by Eridian culture (going by what I know of them from the book I’ve yet to read)
I for one, fully subscribe to the idea that Rocky went a bit crazy in his decades of solitude and became a nudist as a result. He fully set himself free from the buttoned up collar modesty of Eridian society, eating included.
Because Eridians all normally wearing clothing makes total sense for echolocation rock folk. The texture and shape of the fabric ‘blurs’ the 3d image others hear. Even more so if the fabric is thick and sound absorbing. So him wearing a sweater in the books makes sense.
Now, for a eridian to dress up and want be the center of attention, they would want to wear something that is literally loud. Crinkly fabrics, lots of jewelry. A chain mail dress to them would be a sequin dress to us. But to wear such outfits ‘respectably’ is wear them while still wearing underwear. Be cause if you let the decoration bounce against your core, the metal colliding with the stone body will echo and show everyone your hole by sound alone.
And to wear Only the loudest jewelry ever while totally naked?? That’s down right public indecency. The kinda stunt pulled by streakers running across a public sports field for the attention.
The truth comes out about this aspect of Eridian culture over half way to Erid. When it fully hits Rocky that he’s going home and gonna be surrounded by Eridians again. So he should probably start wearing cloths again.
Rocky does not say anything to Grace about it at first, just starts slowly wearing more and more cloths again. Until the day that Grace asks Rocky if he made himself these little outfits to emulate human culture. Something Grace thinks is a really sweet gesture of friendship between species.
“Rocky ask Grace hold onto feelings of friendship when Grace hears what Rocky must confess…”