Traditionally, quenelles referred to small ovals from a finely minced or creamed meat or fish, usually with breadcrumb and egg to bind it, poached and served with a sauce.
These days, pretty much anything in a remotely egg shape is known as as quenelle from chocolate mousse, paté, potato mash or ice-cream. Quenelle is made with 2 spoons (1 spoon scoop is referred to as a rocher).