The Turkey Coquille is not Marabou. Marabou is a soft fluffy feather down the whole stalk. Coquille is soft on the bottom half of the feather. I think it comes from the turkey breast. It is used in dress making for feather collars and trimming. The best feathers are supplied by Veniard for fly tying.
The Alexandra AKA The Lady of the Lake has been a successful fly since 1850 and was so successful it was banned on some waters when it first came out. It has always been one of my favourite wet flies.

BK