Cape May, NJ ark shell or cockle?

[sam wilson]

Hi all,

I'm new to this forum and this is my first post. I am trying to identify a shell I found on Cape May Harbor. I am familiar with the ark shells but have not found one so clean as this one. It leads me to believe that maybe it is a small Dinocardium robustum. Giant cockle?

I know that this species only just makes it to the Delaware Bay so may be rare here so I would like some expert opinions. Unfortunately, I didn't actually collect the shell and only took a photo of it thinking that it was an ark shell.

Thanks!

Sam