These sedentary, stalk-like creatures extend from a hardened shell that protects their bodies from predators and elements. Although the shell ranges from a brown to black, bright yellow tubes emerge to supply air to the organism inside. Fan-like roots extend from the base of the shell, which is usually submerged in moist sand.
Shell weeds settle and attach to the substrate in flood plains or coastal beaches.
Shell weeds use their roots to extract nutrients from the soil. For this reason, they can thrive only in soils rich in organic compounds.
Shell weeds reproduce by fragmentation. As the colony of shell weeds expands, small pieces can break off during physical disturbance. A small piece can be carried by the tide to a new location, where it will attach to the substrate and grow.
As a defense, the tubes retreat rapidly into the shells while squirting a jet of seawater.