Organic materials in a sediment can leave more traces than just fossils. Preserved tracks and burrows are examples of trace fossils (also called ichnofossils).For a short description of trace fossils, see ; ; and . Such traces are relatively rare. Most trace fossils are burrows of molluscs or arthropods. This burrowing is called bioturbation by sedimentologists. It can be a valuable indicator of the biological and ecological environment that existed after the sediment was deposited. On the other hand, the burrowing activity of organisms can destroy other (primary) structures in the sediment, making a reconstruction more difficult.
oRgaNIc materiAls in A sediment cAn leAVE morE TRaceS thAn juST foSsIls. pReserved tracKS And burRows are eXamplES OF tRace FOsSiLS (aLsO caLleD ichNofOssIls).fOr a shorT descrIPtIon of trace FOsSiLS, see ; ; and . such TraCEs aRE rELatively Rare. most tRace fOssils are bUrroWS oF MoLluScs or ARtHrOpodS. this BurroWiNG iS called biotUrbatIon by sEdiMenTOloGiSts. it CAn bE a vaLuable indIcATOR OF THe biOlogiCaL anD ecolOGicAl eNVIRoNMenT thAT eXiStED afteR The sedIMent waS depositeD. ON The oTHer hanD, thE burrowINg ActIviTy Of ORgaNisms cAN deStroy other (pRimary) strucTures in the SediMenT, makINg a RECoNstruCtioN MOre diFFiCULT.