Where did this sps come from???

[ScubaSteve]

Could be cyphastrea, the septa around the retracted polyps does make it look that way. If I recall they can also produce planula asexually, though I've never heard of it in captivity (doesn't mean it doesn't happen).

I've had some poci babies encrust upwards of 1/2" before growing out, so it could still likely be that. I'm still leaning that direction because of the polyp size and density.

Tim, is the whole thing metallic green?