This polychacte lives in its straight tube that protrudes several centimetres from the sediment. The long tentacles are extended from the top for collecting particles. During collecting they are supported by fringe-like extensions of the tube. In case of danger L. conchilega quickly retracts in the tube. When damaged or covered by sediment, the animal rebuilds or extends its tube. This enables L. conchilega to survive in unstable deposits or areas with strong sedimentation. L. conchilega is a selective deposit feeder, ingesting foraminiferans, ciliates, copepods, algae and faeces of echinoderms and molluscs. Laboratory experiments revealed that filter feeding also plays a very important role in its nutrition.
High population densities of L. conchilega are attributed to the combination of periodically high concentrations of suspended matter and the ability to utilize different food sources.
L. conchilega is sensitive to low temperatures and therefore shows low densities in the area of the Wadden Sea after cold winters.