Need help identifying a rock with a story

[LoneWolf8o]

Hello everyone. Names Mike and I'm from Long Island NY. I'd say around 15-20 years ago my Dad found a rock that he thought looked interesting. This was found on Long Island NY. I thought it looked weird and imaged at the time it was a shark head fossil lol. This rock sat in the house for years and managed never to be thrown out. After my Dad passed in 2009 I was looking threw things of his. I noticed this rock and it brought back good memories of us all joking what it was as a kid. So I've held on to it. More recently I had my first child who loves rocks, hes 3. He's always digging for them and looking for them where ever we go. So one day he saw this rock and wanted it. So I let him add it to his in house collection. Now older I felt it was a tool or something from Native Americans or maybe nature did it.

Well last week my sister came from NJ to visit us. She noticed my son playing with this rock and said she has the same thing, "it looks like a heart", which she collects stones that look like hearts. I told her I doubt it has all the distinctive features mine had. So I pointed them all out and she said hers has all of them. Only difference being she says the surface looks veiny. I give that to weathering. Hers was found in central NJ at a river. After seeing the photos of my sister rock, I couldn't believe it and I'm now very curious what these rocks were made for. Since I find it very hard to believe nature could do this. One maybe but having a identical one from another state I find very hard to believe nature did it. A fossil to me seemed unlikely but seeing theirs two now I wonder a little.

I'll include photos with color lines to highlight the parts I found unique.

purple / blue : outside shape
red : marking of some type
yellow : the notch
green : the ridge

My sisters rock is on the red wooden table. I've never seen my sisters rock in person.

Thanks for any info provided.

[ToddsPoint]

They are too much alike and too symmetrical to be natural. I've never seen an Indian made artifact that looks like that so I vote fossil of some sort. Gary

[Kray Gelder]

Cucullaea Vulgaris....a burrowing clam from the late Cretaceous, 65 mil. years ago. These are apparently quite commonly found in the Hornerstown formation, New Jersey.

[LoneWolf8o]

Cucullaea Vulgaris....a burrowing clam from the late Cretaceous, 65 mil. years ago. These are apparently quite commonly found in the Hornerstown formation, New Jersey.

Awesome that's it! Did a quick goggle search and photos that popped up looked the same. Guess its not worth a lot of money, my sister will be sad lol.

Thanks, Now it has more of a story to go along with it.

[IAMZIM]

Cucullaea Vulgaris....a burrowing clam from the late Cretaceous, 65 mil. years ago. These are apparently quite commonly found in the Hornerstown formation, New Jersey.

Thanks for the ID, I have one that is mineralized with a different type of mineral than the one posted, but the exact same shape. It was found in Cretaceous strata in Northern Montana. I was having trouble "matching" it in my fossil identification guide!