Anybody want to take a shot?

[Buckethead]

This is part of a general assortment. I've played around with seeds a few times, but have never seen one like this with three leaves. There are others with two leaves. When it first came up I thought it was a weed or some kind of succulent. But it's obviously a cactus. Anybody want to take a guess of at least which genus it is? I'm really curious.

[majcka]

Some kind of opuntiad I think.

[greenknight]

Yep, "some kind of Opuntiad" is about all you can say at this early stage. As for the 3rd seed leaf - just a freak thing that happens occasionally. I've seen it on other types of plants, and they grew up to be quite normal. Check out this page.