Hitchhiker on turbo snail

[SFREEF3R]

I found these small hitchhikers on a couple of a recent batch of snails. I thought for a moment they were part of the shell but with a metal tool I was able to crush one and reveal a fleshy interior. I was worried it was some sort of a vermetid but under closer inspection the conical shell leads me to believe maybe they are limpets of some kind - though I was surprised to see that they have conformed to the shape of the shell. Anyone else seen these?

 

[Rocks reef]

Are you able to scrape them off? They look like limpets.
@tbrown

 

[Tahoe61]

Slipper limpets?

 

[SFREEF3R]

Are you able to scrape them off? They look like limpets.
@tbrown

I couldn't remove one without crushing it, but inside it was fleshy and the spot it was covering was distinctly lighter than the surrounding region.

 

[tbrown]

Slipper limpets?

I'm fairly certain the white one is a Slipper. The smaller one looks like a normal limpet but could also be a Slipper.