Calvert Cliffs Shell

[cowsharks]

I occasionally find one of these small reddish-brown colored "shells" insitu in large blocks of material that come down from a particular layer of sediment along Calvert Cliffs, MD (Miocene).  The max size for these is about 1/2" in diameter, but most are small like the ones in my pic below. 

 

Anyone have any idea as to what these little "shells" are called?  They only seem to be one piece.

 

Daryl.

[caldigger]

I believe you have Limpet shells.  Of what spieces, I don't know.

[cowsharks]

Someone messaged me to let me know that my little "shells" are actually Miocene Brachiopods, Discinisca lugubris.  Now I have to go research that

 

vr,

Daryl.

[Micah]

Every limpet I've ever seen, fossil or not has groves running from the central point to the edges... so I don't think this is a limpet, instead I believe they are both inarticulate brachiopods from the Tertiary. Discinisca lugubris to be exact as described by @MikeR.

 

 

[belemniten]

I dont know anything about the location and the formation where you found this one.

But i now brachiopods in this condition from Holzmaden:

http://www.holzmadenfossilien.de/inhalte fossilien/Discina papyracea 001.html

Because of that i agree with the Id of the others 

[Al Dente]

Discinisca lugubris is the correct identification for these fossils. The are fairly common in the Miocene and Plio/Pleistocene of the east coast (at least they are here in NC).

 

They are phosphatic.

[caldigger]

Can you show a picture of side profile?  We have Limpets here without any grooves, smooth as a baby's bum.