Such skimmers were used to collect cream from the top of milk. Its curved handle meant it could be hung on the side of a milk basin. Large models such as this one were also used to stir milk curds.
Arminjon, Catherine, Blondel, Nicole, Objets civils et domestiques. Vocabulaire typologique, Editions du Patrimoine, Imprimerie Nationale, 2002, p. 64.