They are sprouts, all attached to the seed. You could not successfully separate them and get multiple plants.
I've had this happen a couple of times and I'm not sure exactly why.
On one occasion I learned that soapy water had been poured into the pot around the time the pit was beginning to split. It's the only thing out of the ordinary I could find. Possibly some chemical in the dish detergent stimulated the seed to put out multiple sprouts. The other time, I was even more clueless about the cause.
What I did was pick the thickest sprout to be primary, and use a paring knife to cut off the other sprouts. The plant grew normally after that.
If it happens again, I think I would leave it to find out the results. An avocado bush?