Ok,thanks again for all the replies
Little update, i think my star fish is in the process dieing.....When i came home today i found him missing one of his legs so he was then a 3 legged star, now tonight i've come home again and he's missing another one of his legs and he doesn't seem to happy. Not sure how he's losing his legs, however the legs he's lost are still moving??
I have another picture for ID
This fellow was out playing with the dropped off leg from the starfish when i turned on the lights tonight (then he went straight back to the rock when i turned the lights on)
Ignore the starfish leg at the back, just the gritter looking thing in front.