cockle vs mussel

cockle

noun
  • The shell of such a mollusk. 

  • The fire chamber of a furnace. 

  • The mineral black tourmaline or schorl. 

  • Any of various edible European bivalve mollusks, of the family Cardiidae, having heart-shaped shells. 

  • A wrinkle, pucker 

  • The dome of a heating furnace. 

  • One’s innermost feelings (only in the expression “the cockles of one’s heart”). 

  • A £10 note; a tenner. 

  • A kiln for drying hops; an oast. 

  • A defect in sheepskin; firm dark nodules caused by the bites of keds on live sheep 

  • Any of several field weeds, such as the common corncockle (Agrostemma githago) and darnel ryegrass (Lolium temulentum). 

verb
  • To cause to contract into wrinkles or ridges, as some kinds of cloth after a wetting; to pucker. 

mussel

noun
  • A freshwater mussel, usually edible, of the order Unionida in subclass Palaeoheterodonta. 

  • A saltwater mussel, usually edible, of the order Mytilida in subclass Pteriomorphia. 

  • Any of certain other bivalves of somewhat similar appearance, such as the zebra mussel and quagga mussel of the family Dreissenidae in subclass Heterodonta. 

How often have the words cockle and mussel occurred in a corpus of books? (source: Google Ngram Viewer )