Large Bivalve Shell

[Fossil N00b]

To preface, I know nothing about fossils or paleontology (hence username). I just stumbled upon this yesterday and thought it was cool.

I was wondering if there is any way to tell how old it is and generally how rare or common this type of find is.

Location is coastal South Carolina Lowcountry. I found it on an island that is part of a public wildlife refuge. You can access a beach on the island. The forested land drops down about 4-6 feet to the sandy beach. I saw the sheer cliff face and thought "I'd bet you could find some fossils in there" and sure enough I saw this sticking out of the dirt/clay so I dug it out.

I am assuming it is very old because it is much larger than any other seashell I've seen on that beach and it has a different ribbed texture. Also I found it far away and higher up from the current high tide line in the dirt (not sand), so it must be from an era where the sea levels were much higher.

It measures 4"x3.75"x1.25".

I'm also wondering what the best way to clean this is?

Thanks, and let me know if there is any more information I should provide.

 

 

[Mosasaurhunter]

Looks like some type of fossilized Cardium clam

[ted coulianos]

Without age/formation or locality data (other than 'low country SC')  I can only give an educated guess as Venericardia  sp. (planicosta?).   If I'm right, then  you were digging in an Eocene age formation, as Venericardia is a guide fossil to the Eocene.  Attached is a link to South Carolina formations and representative fossils:

South Carolina Fossil Sites and Collecting Localities (fossilspot.com)

also check out this entry from a member collection:

Hope this helps, and welcome to the Fossil Forum.  

[hemipristis]

Aka a “cockle”

[Quriosity]

13 hours ago, ted coulianos said:

Without age/formation or locality data (other than 'low country SC')  I can only give an educated guess as Venericardia  sp. (planicosta?).   If I'm right, then  you were digging in an Eocene age formation, as Venericardia is a guide fossil to the Eocene.  Attached is a link to South Carolina formations and representative fossils:

South Carolina Fossil Sites and Collecting Localities (fossilspot.com)

I'd still have a doubt because the hinge mechanism looks more like that of a Cardium (most Venericardia have a very sturdy hinge that seems to be lacking on this specimen).
As mentioned above the exact age is hard to tell without a more precise location. You can check out the USGS geological maps for your area, that'll give you your answer.