Interesting rock found in Salem, Mass US - are these fossils

[Elias]

Hello,

I found this on a stroll near a rocky shore in Salem, Massachusetts. 
My questions:
Are these simple shell fossils? or possibly vertabrae?
any ideas on the minimum age? (how long it would take to turn into this) or the likely age?
This is approximately 5.08 cm (2 inches) at its widest.

It was found at surface level among many other rocks near a fairly well traveled tourist(y) spot.

I realize this is probably overkill for what is almost assuredly a very common thing but I still find the little rock interesting.

 

 

Edited May 1, 2022 by Elias
added a bit more description and one more photo

[Pagurus]

I can't be certain but from the photos it looks like these are the attachments of a modern bivalve shell, Anomia simplex, often called jingle shells. Modern oysters could possibly leave an imprint like this too, but it looks more like the jingle shell (sometimes called a "memaid's toenail" shell). 2-inches is rather large for the jingle shells, though I occasionally find them that size.  In any case, I am certain they are modern bivalve shells and not fossils. Looking at the photo, the rock looks metamorphic to me, like granite or gneiss or something similar. The red spots on the rock are encrusting algae, a modern marine plant. Probably Hildenbrandia rubra, maybe Ralfsia verrucosa as well, especially some of the lighter spots. On a beautiful day like today I do wish I were strolling along the Salem shore, or fishing off the dock at the Willows (though last I heard the dock was still being repaired.) Fossils are unlikely there, as the rocks are mostly igneous or metamorphic, but I haven't really investigated the possibility. I do remember reading that ships once dumped ballast in the harbors, and I enjoy finding bits of old pottery along the shore now and then. Enjoy your strolls! 

[Elias]

Aha!  that 'splains it. It is kind of what I feared but was hoping it was an ancient thing.  Thank you.  So likely this was just bivalve hooking onto this rock (or a few bivalves) for a while recently.  
They tore down the dock at the WIllows by the way. 
 

[Pagurus]

34 minutes ago, Elias said:

They tore down the dock at the WIllows by the way. 

 

Awww.  Thanks, Elias. It's been a few years since I've been there. Before I retired I went to Salem at least once a year, visiting one of the elementary schools with a writing and seashore science program. Fishing and crabbing off the dock, though, had to wait for another day. I'm sorry to hear the dock is down now. If you enjoy walking on the beach and looking for possible fossils your best bet might be down in Rhode Island at a small beach in Portsmouth.