Janthina exigua is one of the smallest species of Janthina. Like their congeners, it builds a bubble raft, which is blown by the wind. The snail cannot swin and will drown if it falls of its raft. It waits until a chance encounter with its prey, the Portuguese Man-o-war, Physallia physalis.
This snail has a circumtropical distribution. Often after a storm, you can find many purple snails as well as its host (one beached specimen shown here).
These photos were taken a day before President Obama visited the Bellow Air Force Station, and the beach was closed to the public.
See the taxonomy of this species at the World Register of Marine Species (WoRMS):
A flock of about 40 birds flying back and forth between Albizia trees at sunset.