From William Finnegan's Letter From Madagascar, "Slow and Steady," in the January 23, 2012, issue of The New Yorker.
Fortunately for the plowshare, the Sakalava people, who inhabit the area, consider eating the tortoise fady (taboo).
The plowshare is a rare species of tortoise. I'm not sure when or how people began using plowshare more than ploughshare; it could be one of those differences between American and British English. Donald G. McNeil Jr.'s July 1996 Times article also had plowshare.
I imagine there was once a more pronounced choice between fady and fadi. Fadi strikes me as further from English.