Giant purple barnacle

Megabalanus tintinnabulum

Family Balanidae - barnacles (crustacea)

Shell conical, made of 6 triangular plates (parietes) fused together with walls (radii) between plates, horizontal striations between plates; color of plates pink to pinkish purple, walls (radii) in between plates with a lighter color, either whitish or light purple; aperture usually round; may be striped and ribbed longitudinally; aperture 1/3 to 2/3 the diameter of the base.
Similar Species
This is most common large pink barnacle in our area. Another non-native Megabalanus, the titan acorn barnacle (M. coccopoma), has been found around the Florida area and the east coast. Distinguishing it from this barnacle is difficult without examining the internal shell parts, which are usually missing when these barnacles wash ashore. The titan acorn barnacle is usually a deep red color with a small (<1/2 basal diameter) aperture.
Gulf, usually attaches to platforms, washes up on beaches in clumps after storms
Maximum Size
5 cm (2 in) (height)
Other Common Names
Previous Scientific Names
M. antillensis, Balanus tintinnabulum