Above is a picture of a  Modiolopsis concentrica  (Hall & Whitfield, 1875) pelecypod fossil. Also the fossil has worm tubes called Cornu...

  In this picture is an Isotelus (Dekay, 1824) trilobite pygidium fossil next to little ringed funnel shapes which are the fossilized remain...

Cornulites worm tube fossil found in the Indian Springs Formation of Crawford County, Indiana. The worm tube is located in the picture t...

Cornulite worm tubes found in the Kope Formation. These small creatures existed in the Ordovician Period. Typically, I find them attached ...

These Rafinesquina brachiopods from the Ordovician Period found in Kentucky have some encrusting creatures on them. This first specimen I ...

Interesting fossils in this picture of a brachiopod shell hosting a number of worm tubes. These fossils are from the Ordovician Period and...

Cornulite fossils on Ordovician Period brachiopods. These brachiopods were found in eastern Louisville, Kentucky at road cuts. Green arrow...

Here is a Devonian clam and brachiopod fused together. They were found in the Jeffersonville Limestone in Clark County, Indiana. It looks ...

UPDATED: I originally posted this as a small horn coral attached to the shell but a series of anonymous comments set me on the correct cours...