You mean, a plant-let complete with root?s -- fairly common in Dendrobiums and other orchids that grow with cane-like stalks -- My Epidendrum does this often. It's common in Dendro's, too - they even have a term for it, Keiki.

Here is a link that might be useful: Wikipedia entry about this topic

Ok so my next question is can I leave it on mother plant or should I remove it? My bromeliads do this but I guess i never thought of another epiphytic doing this.

You can leave it, although eventually it may lose the vascular connection and fall off, at which point you have to plant it -- I just usually stuff the Epi ones back into the original pot, since one is enough in my small house. Or, it may not fall off, and continue to grow as part of the plant for a long time. Hard to say, it happens both ways.

You can leave it on until it gets three inches of roots--either one or two long ones or three short ones. The longer the mother takes care of it the stronger it will get.