Whats inside the little shell growing on top of my hermit crab's shell?

[Gargoyle]

I introduced 1 halloween hermit crab to my nano in September and another smaller one in November. They both arrived in what looks like conus textile snails shells. I collected some shells from a beach near me (I think they're whelk or periwinkle shells), scrubbed them then boiled for 10 minutes before adding to the tank. My bigger crab moved into one of the new shells and the smaller crab moved into the abandoned cone shell. Now I've spotted this little guy who I initially thought was a vermetid snail so I just left him, but his growth rate has surged in the last 2 weeks so that I can now see a white and brown shell. I can see 2 black antennae and a black proboscis that seems to be as dextrous and intentionally moved as an elephants trunk. I reckon it's time for it to leave the tank but I'm 15% sure that it's a very toxic textile snail that hitchhiked inside its mum's shell. Does anyone know what this is and is it safe to pick off or should I be cautious?

 

[CrimsonTide]

Interested... waiting a reply here.

 

[shakacuz]

my guess is a limpet.

 

[BostonReefer300]

Has the little shell moved? I think I see a couple of antennae popping out, but maybe that's just my crappy eyesight. I'd guess it's a small snail at first blush

 

[Gargoyle]

Has the little shell moved? I think I see a couple of antennae popping out, but maybe that's just my crappy eyesight. I'd guess it's a small snail at first blush

No, I don't think it grazes around like a stomatella snail and yes, there's definitely 2 antennae, plus the long proboscis.

 

[Karen00]

my guess is a limpet.

After looking these creatures up, I agree.

 

[Gargoyle]

my guess is a limpet.

Thank you. The patterns on it really look like this attachment so I think you're correct. Perhaps I'll let him hitchhike for a little longer as I don't have any corals just now.

 

[shakacuz]

Thank you. The patterns on it really look like this attachment so I think you're correct. Perhaps I'll let him hitchhike for a little longer as I don't have any corals just now.

they reportedly get to about 3". but nonetheless a good CUC to have