I'm not sure what species your referring to. The International Union of Conservation for Nature, or the IUCN Red List, doesn't have a listing for the Acorn-shelled Barnacle. Considered that this might be a different species, or even a plant / tree, I widen the search and still didn't come up with anything that was close to the name that is listed in this question. As far as I can tell from the IUCN Red List, the Acorn-shelled Barnacle, and the Oak tree, aren't listed. There are over 1,000 species of barnacles, the scientific name, would help to narrow the search for this specific one in question. For more details, see the sites listed below.
why is the southern acornshell endangered
it is not endangered
No, opossum are not endangered
Moose are not an endangered species
Mongooses are not endangered.
Fish that are not yet endangered, are not endangered.
The endangered species are (in order of most endangered) 1.Black Rhino2.Giant Panda3.Tiger4.Beluga Sturgeon5.Goldenseal6.Alligator Snapping Turtle7.Hawksbill Turtle8.Big Leaf Mahogany9.Green-Cheeked Parrot10.Mako Shark
Endangered Species
The emperor penguin is not endangered.
Sadly, the peccary is an endangered species.
endangered
They are not endangered.