I mean, I always thought it was an eye, my researches tell me it’s just an pearl, but did we ever got an oficial explanation?

Here is what I think it is: endermites get inside the endermen, and just like the oysters, endermen creates a hard shell around the endermites and since endermen already have the teleportation power, the ender pearl also have it

I need to know cause I’m going to make real life ender pearls with resin and I need to have sure what is inside them, if I don’t find out exactly what it is I’ll make it just like this classic image