Giant clam shell from Thailand - can I keep it?

[Wiremu]

Hello - 

Am not sure where to post this question, but was certain that this forum would be a good source of advice...

I'm currently in Thailand on the island of Koh Pha Ngan, and been enjoying the amazing snorkeling here.  I found a long-dead giant clam shell in the shallow sands off of our beach, and I'm interested in keeping it. The shell is about 10" wide from end to end and in pretty good condition, but is clearly not a recently expired animal. 

The beach where I found it is Haad Son, and I'm not sure if the entire west coast of the island is a marine protected area or not.  I know some of the beaches north and south of us, near Koh Mah for instance, are protected and no shelling collecting is allowed.

I couldn't find anything definitive on this on the internet and the locals all just shrug when I ask them!

Normally I'm not a shell collector but it's really a neat thing and I'd love to have it as a memento of our trip. However, I don't want to break any laws (CITES?) nor do I want to remove something the is essential to the environment. Since it wasn't the sort of shell that could provide much of a home for hermit crabs, etc., I thought perhaps it wouldn't be missed too badly? 

Can anyone provide me some advice?

Thanks very much in advance.

~William