Spirobranchus kraussii, the blue coral-worm, is a species of marine invertebrate in the family Serpulidae of order Sabellida.

It is native to the Indian Ocean.

[1][2] The head has two rows of feathery branches and a stalked operculum with two pointed wings and a flat cap.

Length about 15mm and tubes are about 2mm inside diameter.

[1] The blue coral-worm builds massive colonies of interwoven calcareous tubes, which can be locally abundant on moderately exposed rocky shores.