Bivalves

[Coryander]

I know this is not Fossil ID, but can someone help me identifying these bivalves?

I found it in Algarve.

Thank you.

 

 

[ricardo]

Hello,

 

Number 2 isn’t a Bivalvia, it is a Gastropoda: Calyptraea chinensis (Linnaeus, 1758).

 

Regards,

 

Ricardo

[Monica]

I think @Max-fossils might be able to help 

[Max-fossils]

Nice shells. I would need to see a picture of the hinges in order to ID them. 

 

Otherwise, from the looks of it, Ricardo seems to be right by saying #2 are Calyptraea gastropods. 

[Coryander]

On 8/30/2018 at 11:51 AM, ricardo said:

Hello,

 

Number 2 isn’t a Bivalvia, it is a Gastropoda: Calyptraea chinensis (Linnaeus, 1758).

 

Regards,

 

Ricardo

 

Thank you.

[abyssunder]

I think, specimen one (1) can't be determined considering it is heavily bored by sponges. It could be labeled as clionaid sponge borings in bivalve shell. 

[Max-fossils]

18 hours ago, abyssunder said:

I think, specimen one (1) can't be determined considering it is heavily bored by sponges. It could be labeled as clionaid sponge borings in bivalve shell. 

I'm not even sure it's a bivalve, looking at the state of that "thing"  

[ynot]

20 hours ago, abyssunder said:

I think, specimen one (1) can't be determined considering it is heavily bored by sponges.

Could 1 be a tube worm colony (heavily eroded)?

[Max-fossils]

10 minutes ago, ynot said:

Could 1 be a tube worm colony (heavily eroded)?

Don't think so. These look pretty different. 

In tube worm colonies, you can really see all those tiny intertwined "tunnels", which don't show up here.

(example from Google)

 

@abyssunder is most likely right. My comment was sarcastic, as I was mocking the very poor preservation. 

But this is pretty clearly a bivalve (piece) that has been affected by sponge borings, such as the one below (which is in much better condition). 

 

(example from Google)

 

With tube worm colonies, all the worms in it are pretty much the same size (in diameter at least), meaning that if you would do a cut section through a colony all holes will have pretty much the same dimensions. On the other hand, sponge borings are very numerous, and have lots of different-sized "shallow" holes. 

 

Now if you look at the specimen in the OP, you'll notice that there are many holes, of different sizes, and that it's a flat surface. (Would it have been a worn-out tube worm colony then there would be fewer holes, all of more or less the same size, and you would've still been able to notice the tubes themselves)

 

Once you start dealing more with invertebrate/seashell fossils, these kinds of details become more obvious. 

I hope this clears it up for you.