Anemone help

[TPATankNano]

So my anemone is generally very happy and hosts two clowns. Every now and then some part of his tentacles will go in and turn this dark green almost black color. Any thoughts?

 

[TPATankNano]

So my anemone is generally very happy and hosts two clowns. Every now and then some part of his tentacles will go in and turn this dark green almost black color. Any thoughts?

Normal look