Entobia is a trace fossil

Trace fossil

Trace fossils, also called ichnofossils , are geological records of biological activity. Trace fossils may be impressions made on the substrate by an organism: for example, burrows, borings , urolites , footprints and feeding marks, and root cavities...

 in a hard substrate (typically a shell, rock or hardground made of calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

) formed by clionaid sponges as a branching network of galleries, often with regular enlargements termed chambers. Apertural canals connect the outer surface of the substrate to the chambers and galleries so the sponge can channel water through its tissues for filter feeding (Bromley, 1970). The fossil ranges from the Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

 to the Recent (Taylor and Wilson, 2003; Tapanila, 2006).

External links

• Bioerosion Website at The College of Wooster
  The College of Wooster
  The College of Wooster is a private liberal arts college primarily known for its Independent study program. It has roughly 2,000 students and is located in Wooster, Wayne County, Ohio, United States . Founded in 1866 by the Presbyterian church as the University of Wooster, it was from its creation...
  
  
• Comprehensive bioerosion bibliography
• Image of Entobia cretacea as a cast showing canals and chambers in three dimensions