In Greek mythology, the Danaïdes (/dəˈneɪ.ɪdiːz/; Greek: Δαναΐδες), also Danaides or Danaids, were the fifty daughters of Danaus. In the Metamorphoses, Ovid refers to them as the Belides after their grandfather Belus. They were to marry the 50 sons of Danaus' twin brother Aegyptus, a mythical king of Egypt. In the most common version of the myth, all but one of them killed their husbands on their wedding night, and are condemned to spend eternity carrying water in a sieve or perforated device. In the classical tradition, they came to represent the futility of a repetitive task that can never be completed (see also Sisyphus and Ocnus).