My anenome split two week ago. I couldn't find the other half until yesterday. It got suck up into my sump all this time. It took me a while to get it out. here are the two parts.
first half
Yes, I noticed separation in the tissue before it split. I also noticed there seem to be a second mouth forming. It also moved like a mad man stinging my fox coral to death(almost)It moved across the tank 3 times before it split.