Spionida is an order of marine polychaete worms in the infraclass Canalipalpata. Spionids are cosmopolitan and live in soft substrates in the littoral or neritic zones.

Spionida. Retrieved May, 08 2021, from en.wikipedia.org/wiki/Spionida.

The Chaetopteridae are a family of marine filter-feeding polychaete worms that live in vertical or U-shaped tubes in tunnels buried in the sedimentary or hard substrate of marine environments. The worms are highly adapted to the hard tube they secrete. Inside the tube the animal is segmented and regionally specialized, with highly modified appendages on different segments for cutting the tunnel, feeding, or creating suction for the flow of water through the tube home. The modified segments for feeding are on the 12th segment from the head for members of this family.

Chaetopteridae. Retrieved May, 08 2021, from en.wikipedia.org/wiki/Chaetopteridae.