Paraconcavus pacificus

{{Short description|Species of barnacle}}

{{speciesbox

| image = Paraconcavus pacificus - inat 4880688.jpg

| image_caption = Paraconcavus pacificus, red-striped acorn barnacle, California

| name = Red-striped acorn barnacle

| genus = Paraconcavus

| species = pacificus

| authority = (Pilsbry, 1916){{cite book|editor-last=Carlton|editor-first=James T.|last=Newman|first=William A.|chapter=Cirripedia|pages=475–484|title=The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon|date=2007|publisher=University of California Press|location=Berkeley|isbn=978-0-520-23939-5|edition=4th|ref=carlton-2007}}{{rp|483}}

}}

Paraconcavus pacificus, the red-striped acorn barnacle,{{cite book|last1=Sept|first1=J. Duane|title=The Beachcomber's Guide to Seashore Life of California|date=2002|publisher=Harbour Publishing|location=Madeira Park, BC, Canada|isbn=1-550172514|page=164|edition=1st|ref=sept-2002}} is a species of balanid barnacle known from subtidal sandy habitats of the outer northeastern Pacific coast, from Baja California north to Monterey Bay.{{cite book|last1=Morris|first1=Robert H.|last2=Abbott|first2=Donald P.|last3=Haderlie|first3=Eugene C.|title=Intertidal Invertebrates of California|date=1980|publisher=Stanford University Press|location=Stanford, California|isbn=0-80471045-7|oclc=7043400 |edition=1st}} It grows to 35 mm in diameter, with pink longitudinal stripes over white plates, and can be distinguished from other large, pink-striped barnacles in its range (e.g. Amphibalanus amphitrite) by the longitudinal striations across the growth rings of its plates. While it will attach to many different kinds of hard substrate, it shows a preference for attaching to the shells of other organisms, particularly sand dollars.