Strange creature

Today my choice is for this very strange creature...

If some body know what it is , it will be nice to know...

It is on a fire coral in ...you can see the details of the coral...

The creature is red or brown, The two chimney were open like on the picture and close when the camera was closer...
The size is 10 cm or so...

If you know what it is thanks for the comment...I never saw that.