Balanus crenatus is a species of acorn barnacle in the Balanidae family. Balanus balanus is a species of acorn barnacle in the Balanidae family. Amphibalanus amphitrite is a species of acorn barnacle in the Balanidae family. Semibalanus balanoides is a common and widespread boreo-arctic species of acorn barnacle. Whale barnacles are species of acorn barnacle that belong to the subfamily Coronulinae, family Coronulidae. Amphibalanus eburneus, the ivory barnacle, is a species of acorn barnacle in the family Balanidae. Its common names include the striped barnacle, the purple acorn barnacle and Amphitrite's rock barnacle. Amphibalanus improvisus, the bay barnacle, is a species of acorn barnacle in the family Balanidae. The acorn barnacle is a moderate-sized barnacle with a diameter of up to .