They are organisms that feed on acorns from sea. Also you could say them better cirripofago, anatifafago or percebofago, to avoid the risk of misinterpretation, because Furoya is right in the other two forms of balanus or Glans, Acorn (fruit) and Glans. He clarified that the Acorn of the sea, which is a cirripedo crustacean, which is abundantly in estuarine areas influenced by tides, also receives the names of anatifas or barnacles (Balanus, of the family Balanidae genus). For this reason, a balanofago can be any type of bird that eats "shells" in the beaches, especially those that are attached to small rocks or logs. It is also a balanofago that eating barnacles or anatifas, which is a seafood especially felt on the Cantabrian coast. Also, by extension could be a squirrel, feeding on acorns, but those of the trees.
It should be clear that the balanofago does not feed necessarily acorns as fruit, but rather a type of crustacean called "sea Acorn". Although in Greek 946; 945; 955; 945; 957; 959; 962; ("barnacle") is the name of the fruit, to the Spanish comes as a cultismo to name to a genus of animals, crustaceans, and Acorn (from Arabic) for the vegetable. In addition, nipple or Glans is synonym of Glans, so that a balanofago could also be who assiduously practiced fellatio.
