Where did i got this rock?

[KING KONG]

So while cleaning, I found this beautiful rock under the sand.

I noticed a clam/oyster like thing sitting on top of it which suddenly gone under the sand. What can be that? It was of green colour with some designs.

 

[His Coral Highness]

Oyster shells

 

[KING KONG]

Oyster shells

So what i saw going inside the sand is an oyster?

 

[His Coral Highness]

So what i saw going inside the sand is an oyster?

Probably not, they don't really move once they're attached

 

[KING KONG]

Probably not, they don't really move once they're attached

Ooo I seen something green coloured and gone under the sand. It looked like oyester or clam. It was resting on it and then ran away inside the sand. Probably I'll search for it again tomorrow under the sand