Are these Clams on this Snail?

[HTXReefer]

This snail came as a hitchhiker on some live rock. Is this a clam attached to the snails shell?

 

[Reefing102]

Yep. Looks like clams or mussels (filter feeders) Most will usually die off and their shells will stay

 

[austibella]

Cool Looks like it to me

 

[WheatToast]

Yep. Looks like clams or mussels (filter feeders) Most will usually die off and their shells will stay

Or maybe oysters as well. OP could try to keep them alive with Phytoplankton dosing (which would also benefits other filter-feeders and pods), but that would elevate nutrient levels.
P.S. I also spot barnacles on the snail. I believe their care requirements are similar to those of non-photosynthetic bivalves (ex. the clams, mussels, and oysters that have been mentioned on this thread).

...on some live rock...

Where did you obtain the rock?

 

[polyppal]

look like oysters to me too, cool though likely won't survive

 

[HTXReefer]

Or maybe oysters as well. OP could try to keep them alive with Phytoplankton dosing (which would also benefits other filter-feeders and pods), but that would elevate nutrient levels.
P.S. I also spot barnacles on the snail. I believe their care requirements are similar to those of non-photosynthetic bivalves (ex. the clams, mussels, and oysters that have been mentioned on this thread).

Where did you obtain the rock?

I got the rock from KP Aquatic.

 

[jhuntstl]

I have a very similar bivalve attached to a Trochus that's been in the tank for nearly 4 months. It's doubled in size. I do feed phyto!

 

[polyppal]

Couple of barnacles on the back too, that’s pretty cool. Poor snail prob has back problems

 

[salty joe]

The snail looks like it might be a sundial, a predator of zoanthids IIRC.

 

[WheatToast]

The snail looks like it might be a sundial, a predator of zoanthids IIRC.

From what I have read, their shells are pretty flat, so I would doubt it.