Some sort of stone with a ton of fossil shells?

[moodorf]

I found this down near the Genesee river here in NY today. It's strange compared to the other fossils (if this is one) I've found out there--instead of a handful of specimens, it seems to be riddled with mostly 2 or 3 different types of small, pistachio-sized sea shells. The outside of the rock is pockmarked where (presumably) shells had made impressions but had fallen out before fossilization. This rock has this sparkling luster in a couple small spots, mostly on the large fossil shell fragment (?) I'm seeing, and a few of these curious grape-like formations. The biggest these white grape like clusters is going down into a shallow earthworm sized cavity into the rock. 

 

So yeah, I don't even know how I would describe this rock, other than I think it has fossils, and I think it's chert. I also wish I could give you a really nice shot of one of the individual shells, but many of them as you can see are like 2/3 within the rock so it's hard for me to get a handle on their shape. I'm also not super knowledgeable on Fossilized sea shells unfortunately. 

 

help?

 

Edited October 23, 2021 by moodorf

[Lone Hunter]

There's a lot going on in that rock!  The sparkly places look like drusy quartz or some kind of mineral.  

[FranzBernhard]

My first impression is lots of brachiopod molds in somewhat druzy rock. But I could be completely wrong, though.

Very probably, someone here on TFF is able to recognize it at a glance.

Franz Bernhard

[hemipristis]

1 hour ago, FranzBernhard said:

My first impression is lots of brachiopod molds in somewhat druzy rock. But I could be completely wrong, though.

Very probably, someone here on TFF is able to recognize it at a glance.

Franz Bernhard

I concur.  Looks like chalcedony replacement.

 

Cool find!  I bet if fluoresces nicely