Brown circle on wall hammer

[Eric.jones1996]

Can anyone help identify what this brown circle thing is on my wall hammer? Is it something I should be worried about? I tried to scrape it off with some tweezers but didn’t budge.
Thanks

 

[MnFish1]

@vetteguy53081 will know. Does it move?

 

[vetteguy53081]

Looks like a keyhole limpet
If not, ostrapod or isopod are other possibilities. Pic a little fuzzy and dim to confirm
Shining a flashlight on object and snapping photo often helps

 

[Eric.jones1996]

Looks like a keyhole limpet
If not, ostrapod or isopod are other possibilities. Pic a little fuzzy and dim to confirm
Shining a flashlight on object and snapping photo often helps

I tried to get some better photos. It hasn’t moved at all and is maybe about 0.5 of an inch in diameter

 

[vetteguy53081]

Hmmm, may be a new head but looks like some type of coral growth
Don’t think it’s a tunicate