On a recent and much treasured trip to the ocean, I came across strands of tiny shells on the beach. Of course I was curious. Clearly the shells had once belonged to living mollusks. But why were they all connected together like a necklace or bracelet? Because of a worm.

A decorator worm to be exact. These segmented worms live in benthic environments and create the tubes out of mucus that also cements sand, shells, and other debris available in their habitat to the outside of the tube. The appearance of the decorated tubes of these worms vary greatly by habitat and what’s available. The tube serves as the worm’s home and armor.

The worms themselves look like see-through millipedes with long antennae and plumed gills on their head. For their size, the decorator worms have large jaws for eating plankton as well as decomposing plant and animal matter on the seafloor. Another fun fact – the decorated tubes not only protect the worm but also collect food!