The AI would confidently give him the wrong answer, since it has no way to provide the correct answer, and doesn't know its own limitations. (Or however you wish to describe "hallucinations", which is about as accurate as my description ;))

And he would think he has the right answer, perhaps write up an essay about his findings, which later AI bots will read and learn from, propgating the mistake...

Wait, the author identified the shell as "Sphincterochila candidissima". Which is a living species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk. Completely off.

The AI would confidently give him the wrong answer

There is irony here that does not sleep.