Found in the Philippines... gastropod?

[annasea]

Found this while in the Philippines last month. Dr Bill thinks it might be a gastropod, but my googling turns up nothing.

 

[knotical]

Perhaps Corculum cardissa (heart cockle)?

 

[annasea]

Based on a quick Google, I'd say yes. Thanks so much, knotical!

 

[drbill]

When Anna contacted me, I had suggested it might be a gastropod based on the third image, but looking more closely at it I agree it is a bivalve. The first two pictures almost made it look like a pair of Argonauts to my aging eyes!