What fossil is this?

[Archie 00 00]

It was found on a beach in conglomerate rock in Wenderholm Regional park near Orewa above Auckland in New Zealand.

it is 20mm long and 8mm wide

 

Edited January 2, 2020 by Archie 00 00
I didn’t give the size of the fossil

[Ludwigia]

At first glance, it looks like a piece of bivalve shell.

[Strepsodus]

I suspect this is not a fossil unfortunately, though I may be wrong.

[Dave pom Allen]

i ll go a piece of a bivalve