In Catalan we call it arrova. It's interesting that, used as a unit of mass, the @ had different values in different places [1][2]:

- Castille: 11.5002325 kg

- Aragon: 12.5 kg

- Catalonia: 26 pounds

- Valencia: 30 pounds

- Portugal: 32 pounds

Apparently it's still used as a unit of measure in Spain and South America, for example for oranges [2] and cocaine [3].

[1] http://ca.wikipedia.org/wiki/Arrova [2] http://es.wikipedia.org/wiki/Arroba_%28unidad_de_masa%29 [3] http://web.archive.org/web/20110101190636/http://www.delisse...