Enzo,
I assume your talking about the purple an green one, he is a cerianthid anenome(family pachycerinthus mana), refered to as a tube anemone.
I have found almost every article on them contradicts the next, They are non photosynthetic,night feeders who prefer a soft sandy substrate in which to bury there body. Mine stays open in the day w/ the halides on,but really opens up at night, or under lesser light. I feed it around a quarter inch piece of shrimp once or twice a week, and it has grown tremendously.When I got it' body was about the size of an average fanworm about 2 1/2" or so,its now around 9" or so long and about as thick as a graden hose with tenticles reaching out a good 8"s.
They do have a powerful sting,and I wouldn't recommed keeping one w/ small bottom dwelling fish or clown fish who may attempt to host w/ it.
Aj
Thanx for the positive comments guys, I spent alot of time on the rock scape, I had to drill and rod the cliff on the Left, but the rest is just good old balance.
Aj