Not sure what this is

[H.Greenleaf tank]

Wife found this in the tank. I have no clue what it is. Any help with be grateful. New tank 2 months old at the end of diatom cycle.

 

[Gumbies R Us]

#reefsquad

 

[tbrown]

Looks like a possible Operculum from a snail. That's basically like the door to their shells. Did you recently lose any Turbo Snails? That one looks like it has a little flesh on it which means it's probably fairly fresh/recent.

 

[Rocks reef]

Wife found this in the tank. I have no clue what it is. Any help with be grateful. New tank 2 months old at the end of diatom cycle.

Can you flip it over and get a pic?
It looks like something was dropped in the tank or came off a piece of equipment. I'm guessing here.
How big is it?