This has been growing in my tank for over a year from a very small piece to 3-4 inches in diameter. It is growing in darker place in the aquarium, it it white- yellow.
Thank you for your response. My tank seems to be doing well. For some reason all different type of Montipora and cyphastrea went from 1/2' to 4-5 inches in a year. We are selling our house in CA and relocating to AZ next month and I must admit that I am having anxiety attack about moving the tank....