It looks like a Polynoidae scale worm most probably Harmothoe impar but it'd be hard to be sure without seeing the scales and possibly the chaetae up close to be sure which species.
Yes they are tube worms surrounding it, belonging to the Serpulidae family, probably Spirorbis species.
It also looks like you have a small patch (above/right of the scale worm) of the colonial sea squirts Botryllus schlosseri
