Help with my t. maxima

[Leopardshark]

Hello, ÃÂ*´m placing the thread in here because i didn´t have much luck i the general forum. I just purchased a t. maxima yesterday at night, I placed her on a rock and she fell off 2 times to a lower rock, so i placed her again in the upper rock.
So, until now the clam hasn´t opened yet a bit.
IS this normal? I mean the clam has been on the tank for 12 hours, but shouldn´t she be opening just a little bit?
Here´s the pic. next to my t. derasa which is fully opened. (BTW the derasa has grown almost 50% of it´s original size in 4 months).
In how many days should the maxima start opening? or is it time to take her back to the lfs?.
I´ve read that maximas are less hardier than derasas, so any extra info you can provide will be very appreciatted.
thanks

the pics is in here (http://www.reefcentral.com/vbulletin/showthread.php?s=&postid=491301#post491301)

Update:Now i know what possibly happened. A few moments ago i picked up the clam to place it on the substrate, and there were at least4 bristle worms (i think those are the red little worms right?) on the shell, maybe they were feeding on her. I took away all the f*°[ing worms and placed her on a rock on the substrate.
But now the question is why did the worms were all over the maxima and don´t bother the derasa?
Any idea?

[reefrunner69]

When a clam is first placed in a tank it is stressed and secretes a mucus from its byssal gland, this mucus has the effect of a aromatic meal to a starving person to any of the worms, crabs, shrimp etc... they then begin chowing down on the mucus thereby causing more stress and more mucus. 12 hours may be a bit soon to see the clam open if it does not feel secure (ie..toppling over), now that it is on a more stable substrate, I would expect it to begin attatching byssal threads and slowly beginnibg to open over the course of the next day or so.

[Leopardshark]

Thanks Kevin for that great answer. I hope the clam start opening soon, i know there has been a lot of stress since she has fallen from the rock 4 times and then i shaked her to get rid of the worms.
She is in a more stable substrate and i hope she will open soon.
BTW the little visible part of mantle shows no traces of desintegration or something like that.
Thanks again:)

[Leopardshark]

Ok, so the clam is officially dead.
No thing more to say but that i´m taking her to the lfs today and ask for a refund:(