When Grace picks the name "Rocky", to a human audience, it's kind of like a little joke, right? Oh haha, it's because he looks like a rock, plus a movie reference, right?
But what if the Eridians hear it very, very differently?
Eridians kind of ARE rocks, in more than one way, aren't they? Their outer appearance resembles rocks; and (this might be fanon, I don't recall right now) their *brains* are crystalline structures. They hatch from eggs that probably look like rocks. The environment they live in presumably contains rocks.
What if Eridians view rocks in a kind of reverent, aspirational way? Like "For rocks you are, and to rocks you shall return" but with less of a dismissive/humble tone and more of a "we are fundamental building blocks of reality in every form we take" thing.
And then Rocky is explaining to Eridian linguists who are studying Grace's English what his "human name" means, in English, and the linguists are giving him scandalized side-eye and going "So you met an alien and you told him that THAT was your name? [Wow, what kind of arrogant prick would do that?]" And Rocky is like, "no no nonono, I absolutely did not tell him that was my name. I gave him my real name! Grace picked that name for me, he didn't even ask me for suggestions, I had nothing to do with it! It was like right after we first met properly -- it didn't seem like he even had to think very hard about it."
The linguists question Grace about his reasoning, of course, and Grace is a little embarrassed because he thinks this is a "haha our human is bad at naming things, he found a Tau Ceti amoeba and named it Taumoeba, silly human!"
(Also, he does not want this to end up leading to a movie night where the first movie he has to show a bunch of ALIEN LINGUISTS is Rocky. Just seems like kind of a genre-mismatch, right? And Disney's Atlantis: The Lost Empire is *right there*. Or he could pick some movie that showcases a bunch of different real human languages really well, or... Something that's not a sports drama film.)
So he brushes it off a little, saying something like "Well, sure, it wasn't hard for me to decide to call him Rocky. I mean, it's kind of the obvious choice, yeah?"
And the thing is. It's established knowledge now that all humans can perceive things that Eridians can't perceive. It's not even like superstitious "ooh spooky aliens" woo-woo. Respected, credentialed Eridian biologists have confirmed that humans have *actual, physical organs* that let them detect phenomena that Eridians cannot detect.
So what the Eridian linguists are hearing is that this alien met Rocky, observed Rocky with its strange alien powers of perception, and immediately chose to give Rocky a name that conveys "you resemble the fundamental core of what all your people essentially are and aspire to be". And he said it was obvious.