1) Modern obsolete currency 
The Stelo (`star`; plural: Steloj ) was from 1945 to 1993 a monetary unit of Esperantists, one of whose aims was to achieve a single world currency. Attempts at an earlier currency, the Speso, with derived units like the Spesmilo, were cut short by the First World War. For a time the Universal League (in Esperanto: Universala Ligo), an arm of th.....