Too small? Sounds like a challenge to me! Hopefully they’ll still have 'em towards the end of next week.
Because I’m sure everyone wants to know the scientific names:
Akagai (Japanese ark shell clams) are Anadara broughtonii
Blood arks from Mass. are Anadara ovalis
And Mexican blood clams (or less glamorously “pustulose arks”) are Anadara tuberculosa
I couldn’t find any phylogenetic information (i.e. which are more closely related). Sure would be fun to do a side-by-side taste test of all three!