Help Identify

[deepcreek]

I've had this since I was a kid.  It was a gift from an elderly neighbor's rock collection.

 

To me (a curious layman aka numbskull), it looks like a fossil.

 

I'd appreciate any insight you can offer.

 

It weighs 325 grams and is 79 x 62 x 70mm.

 

Many thanks!

 

Joe

[deepcreek]

A couple more photos.

[Herb]

nice mollusc steinkern ( internal cast)

[Tidgy's Dad]

Yes, a bivalve mollusc steinkern. 

Nice one too. 

[abyssunder]

I agree with the others. Nice bioerosional markings on it. Hard to tell of which bivalve it is from, so my thought of Arctica may be just a guess.

 

picture from here

[deepcreek]

I want to express my sincere gratitude to @Herb, @Tidgy's Dad, and @abyssunder for the super fast response in answering a question that has nagged me for decades.

 

That is so cool and has led me to do more research on steinkern fossils.

 

And I just remembered that I had another one gifted from the same sweet lady. 

 

I assume it'is also a steinkern fossil.

 

170 grams 

78 x 71 x 27mm

 

Many thanks!

 

Joe

[Coco]

Hi,

 

The second fossil is a gastropod operculum.

 

Coco

[Tidgy's Dad]

Yes, operculum, and looks modern too. 

[Max-fossils]

Welcome to TFF! I agree on the given ID's. First one is a bivalve steinkern (and a fine one at that too!), second is a modern gastropod operculum (looks kinda sea-worn too). 

In case you're wondering what an 'operculum' is, it's pretty much a protective 'lid' for some snails:

 

("Cat's eye" is a very informal name, and not used much scientifically to my knowledge)

[Herb]

nice operculum

[abyssunder]

I agree with operculum.

[deepcreek]

I really appreciate everyone's help.

 

What a great group of folks!