Their feeding and hiding activities involve a certain amount of burrowing and other moving about of sediment. Some fungi, algae, sponges, worms, gastropods, bivalves and echinoids all do this. Boring species are associated with shallow water and their holes therefore can indicated the position of a paleoshoreline. The borings are typically filled with the sediment of the overlying bed. Some worms, arthopods, mollusks and echinoderms burrow.
Most burrows serve the dual purpose of shelter and a place to feed.
Some burrows shelter the bulk of an organism while it reaches out into the water column to feed on suspended particles. Others are complex networks that reveal the organism's ecology. Each burrowing species has a characteristic burrow architecture and many species have preferred depth habitats. Their burrows can therefore help to reconstruct paleodepth. Tracks are individual imprints left by the passage of an organism over the sediment surface.