1+ towards Adorkable's comments on placental fusing.
I have triplets and two are identical and one is faternal. Their placentas fused. Ours (after birth) were classified as tri/di as in tri-amniontic/di-chorionic. However I had one fused, massive placental mass by about halfway through the pregnancy. It was commented that it was crazy big. Crazy big LOL.
ETA: for fun and stats (if anyone cares to calculate LOL), they were spontaneous and are all girls. We have 5 girls ;)