Is that the horse egg from the old tutorial Easter egg? I think i have a few of those their pretty cool item
I believe That this is From the old tutorial Easter egg. When you spawn the horse it will be tamed, have a saddle and be fully grown up, It will however Gain its Stats.
Yep all true, I can't see it going for more than about 5k though because it's kinda just a novelty because it doesn't have a special name.