Hugh Nibley writes:
"They have plenty of iron, accarum, and andanicum," says Marco Polo of the people of Kobian. "Here they make mirrors of highly polished steel, of large size and very handsome." The thing to note here is not primarily the advanced state of steelworking in Central Asia, though that as we have seen is significant, but the fact that no one knows for sure what accarum and andanicum are. Marco knew, of course, but since the things didn't exist in Europe there was no western word for them and so all he could do was to call them by their only names. It is just so with the cureloms and cumoms of Ether 9:19. These animals were unknown to the Nephites, or else though known to the Nephites, they are out of our experience so that our language has no name to call them by. They were simply breeds of those "many other kinds of animals which were useful for the food of man." [Hugh Nibley, Lehi in the Desert and the Word of the Jaredites, pp. 217-18]
Note* It is also possible that while Joseph Smith had no knowledge of these animals in order to translate, they since have become known to us. It is hard to know if Joseph had a knowledge of the animals of Central America (or South America). [Alan C. Miner, Personal Notes]