Connecting the environment of the ancient past with the natural and cultural history of yesterday and today.



Identifying Fossils on the Fossil Beds

Images on this page can acquaint you to the variety of corals and other fossils that can be observed on the fossil beds when the river level is low. Most are on the coral beds that are usually visible during the late summer and fall. Reading the River Level chart, [link here] when the lower gauge listing is below 13.5 feet the coral beds are exposed. If the lower gauge reading is below 24 feet only the upper fossil beds along the river’s edge are exposed.

"Tusk" coral - Siphonophrentis elongata   Large horn coral Siphonophrentis elongata (commonly called a “tusk” coral) surrounded by other corals – dry and wet. Water makes the fossils more visible by darkening the limestone surrounding the fossils. This only works where the fossil beds are not coated with silt. Visitors are encouraged to bring water or a large cup to pour over the fossil beds for the best view.

Pipe organ coral - Acinophyllum

Colonial coral Acinophyllum, commonly called a “pipe organ” coral. It is related to horn corals.


Aulocystis, commonly called a “tube” coral

Colonial coral Aulocystis, commonly called a “tube” coral. It is related to “honeycomb” coral.

Favosites commonly called “honeycomb” coral

Colonial Favosites commonly called “honeycomb” coral are very common on the fossil beds. It superficially resembles a beehive.


Pleurodictyum - "wasp nest" coral

Pleurodictyum is coral that resembles a wasp or hornet’s nest. It is a “honeycomb” coral with larger chambers.

branching colonial coral Thamnopora

The branching colonial coral Thamnopora. Intact colonies like this are widespread on the fossil beds.


massive branching coral Favosites (Emmonsia) ramosa

The massive branching coral Favosites (Emmonsia) ramosa forms very large colonies but not common.

Eridophyllum - “pipe organ” coral

Eridophyllum “pipe organ” coral on the upper fossil beds.


rugose coral Prismatophyllum

Colonial rugose coral Prismatophyllum is the same as the ‘Petoskey Stones’ of Michigan.

Honeycomb coral and stromatoporoid

Compare the texture of the "honeycomb" coral on left and the stromatoporoid sponge on the right. The holes are from small horn corals within the sponge.



This stromatoporoid sponge looks like a wrinkled rock. The skeletal
structure is very small requiring a magnifying lens to be seen.

Large horn coral Heliophyllum

Large horn coral Heliophyllum verticale. Note the numerous other corals.


Long, skinny Tabulophyllum coral

Tabulophyllum is a horn coral that can be a centimeter or two wide and up to 30 cm long. It resembles a snake, but the fossil beds pre-date reptiles!

Turbonopsis snail

Rock layer covered with large Turbonopsis snails, brachiopods and corals. This is on the upper fossil beds.


Joint fracture in fossil-rich limestone

A calcite-filled joint fracture cuts across fossils. This is a stress fracture in the limestone bed rock.

Additional Fossil Photographs

As you can see from these images, the fossils at the Falls of the Ohio come in a variety of shapes, patterns and sizes. The upper fossils beds (among the trees) contain great diversity of creatures and are exposed most of the year. The coral beds (lower fossil beds) have the largest fossils exposed here, however they are only visible when the river level is very low. Remember – take nothing but pictures, leave nothing but foot prints!

Another fossil identification guide on this web site: Devonian corals

Rocks that look like fossils: Pseudofossils

Updated July 2, 2014