Smallest Frag?

I had an Acro rtn on me a few years back. I was able to frag 1/8 of an inch off it. It lived another year after that. It's amazing what these corals can live through.

 

Birds nest about 1 inch and it has grown one inch taller and has many other branches or run offs from it. It was one single branch to start out. There is another that broke off another Birds nest I have so I am going to pull it out and put on a frag. what the hell.

 

I had a red digi that I must have accidentally fragged and a piece got caught in a rock, because weeks later I started noticing a small bit of growth. It turned into its own mini colony by the time I sold the tank. The frag would have had to me mere milimeters in length initially, else I think I would have noticed it sooner, and I don't think this was a case of sexual reproduction.