Serpula vs Serrula - What's the difference?
serpula | serrula |
(zoology) Any of numerous species of tubicolous annelids of the genus Serpula'' and allied genera of the family ''(taxlink) that secrete a calcareous tube, usually irregularly contorted, but sometimes spirally coiled, with a wreath of plumelike and often bright-colored gills around its head, and usually an operculum to close the aperture of its tube when it retracts.
(Webster 1913)