Where did this sps come from???

[ScubaSteve]

It looks like a baby pocilipora damicornis. P. damicornis is one of the few sps that produce planula asexually, especially in captivity. Mine produces mini colonies regularly in random spots around my tank (even my sump) and look similar to yours when first starting. Could easily be from your other spawning event also, but more than likely its a poci if you have one in your system somewhere.

[TimT]

I have had a few damicornis randomly show up so what you say makes sense. The only thing is they usually only encrust about an 1/8" and then start growing upwards. This one is encrusted about a 1/4" or so and is a metallic green. Not a colour I have ever seen on Pocillpora. I'll snap another pic of it and you can see what I mean.

[Acrowhora]

My birdsnest spawned recently,and found lotsa babies all over my live rocks.at first I wasn't sure what they were,so left them all til they got big enough for me id.i thought they were pest anemones but good I didn't kill,as I later found out that they're birdsnest