Yeah, it's a similar situation to octopus -> octopodes/octopi/octopuses. There's the native English pluralization (octopuses), the Greek pluralization since "octa" and "pous" are Greek words meaning "eight" and "foot" respectively - and the Latin pluralization, since English borrowed octopus from Latin, not Greek, which is why octopi is the older pluralization in English. I've also heard it said that "polypus" (many feet) was the name for the creature in ancient Greek, but I've also seen it said that was the name for it in classical Latin as well, so who knows.