[13of40]

I visited a farm in British Columbia about ten years ago that was raising bivalves (geoducks I think) and they'd worked out how to raise them all the way from fertilization through all the microscopic stages. In retrospect, they probably had to do that because clams aren't polite enough to attach to something, en masse, that you can collect on the beach.

[pvaldes]

Is because baby clams have a lot of predators, specially crabs and starfishes, so they mums either nurse it under the shell, or try to spread it for the widest area possible.