Alitta virens (common names include sandworm, sea worm, and king ragworm; older scientific names, including Nereis virens, are still frequently used) is an annelid worm that burrows in wet sand and mud.

As of 2006[update], the population of sandworms had diminished greatly over the preceding few years due in large part to overharvesting before the worms are able to reproduce by spawning.

[citation needed] Sandworms are also essential to the study of the investigation of metal uptake in marine biology.

[5] They have many distinctive traits, including: The parapodia function both as external gills (the animal's primary respiratory surfaces), and as means of locomotion (appearing much like short legs).

[citation needed] Usually, sandworms are gonochoric, meaning that they reproduce sexually between the males and females of the species.