During the Acolytes' attack on Xavier's Mansion that was ordered by Fabian Cortez, Barnacle struggled with Storm, but was defeated. Fabian fled, leaving Barnacle and Acolytes. They asked for asylum but Professor X refused.
Barnacle lost his powers on the M Day.
Barnacle was created by Fabian Nicieza and Alan Davis w/ Lee Weeks in 1999 and first appeared in X-Men: Magneto War #1
It has been stated that he is working with Selene during Necrosha.
Barnacle could create a chemical reaction that solidified moisture into a hardened shell. He also could shoot spray of barnacle-like crust.