In the 17th century, based on a question raised by the Bishop of Quebec, the Roman Catholic Church ruled that the beaver was a fish. The legal basis for the decision probably rests with the Summa Theologica of Thomas Aquinas, which bases animal classification as much on habit as anatomy. Therefore, the general prohibition on the consumption of meat on Fridays during Lent did not apply to beaver meat.
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So I guess land sharks are are forbidden during Lent?