I don't know but if they are open before you cook they are bad.

I think they should be open all the way around but don't have to be open wide, if that makes sense.

yeah, by the time I found info they were overboiled - some were wide open, some just barely

less than about 3/8 of an inch after boileing.

But then you can easily open them or halve them to make a nice presentation.

thanks kdfrawg