The catch? I asked it on Russian) And Russian name for guinea pig is "morskaya swinka" (rus. "sea piggie"). It's a very-very old term, that initially was "zamorskaya swinka" (rus. "piggie from over the seas", i.e. from distant countries). And... well, ChatGPT 3.5. did not know what exactly "morskaya swinka" means. It knew that it's some kind of pet, and it assumed that it's a sea animal) So the result.
It's the sort of mistake a human could easily make, and the sort humans *do* make. We see the same sort of thing here on the SPF; it is dominated by native English speakers, using English, American, Aussie, Canadian, etc. idioms. Which are often misunderstood not only by non-native English speakers, but by *other* English speakers.
This has resulted in confusion and occasional irritation, but it's generally cleared up fairly quickly by a question and explanation or two. AI needs little more than that.