What is this on my Rock Flower Anemone?

[CapeCoralDan]

I got this guy yesterday and this thing under him showed up today. I don't have any rock like this in my tank and didn't notice when I put him in. Is it just a stone or something else? I tried to poke it out, but he won't let go of it.
Just curious.

 

[KrisReef]

These animals attach their feet to the substrate, in this case it looks like pebbles of some kind. Don't mess with an anemone's foot they are delicate and prone to tear. That can be fatal ime.

 

[CapeCoralDan]

Thanks, I didn't pry too hard. I'm pretty sure it's a rock from the aquarium store where I got it. Was just making sure