IMO they are Actinodiscus Mushrooms These corals display a wide variety of colors, textures, and patterns. Some are solid colors, whereas, others are striped or spotted.
In general, they need a medium light level and a low to medium water flow they are semi-aggressive and require adequate space between themselves and other corals. Below is a pic I just took as you can see I keep mine on the substratum.
Yup, thought I said that in post #3...... :rotfl:
Thx for the conformation joe :laughing: