Cancale's greatest reputation comes from the oyster market. Here several oyster vendors setup and sell a variety of types at incredible prices. A dozen local oysters for €4-5 is remarkable. And they are good ones too with a strong flavour and touch of metallic. The lemon and bread from the nearby supermarket mopped the flavours well.
I preferred the standard shaped creuses than the unusual oblong longues. Perhaps the creuses were just a little bit sweeter. I also sampled the famous belon at €3 each (and the stallholder said the €4 pied de cheval weren't much different) which were a little meatier. But at 6x the price, I'd be happy going for the sets of dozens.
After eating the oysters, the shells get discarded to the oyster graveyard littering the floor and serving as a scrap heap for the seagulls to pick from. It's not a bad life.