The colour looks to me to be just a little too blue & transluscent for it to be a sea pearl. However, from Paul Humann:
Dark green spheres with bright reflective sheen. Often covered with thin, silvery to light lavender algae. Attached to substrate by thin, hair-like runners. One of the largest single cells found in either the Plant or Animal kingdom.
Common to occasional in S. Florida, Bahamas, Caribbean.
Grow in most reef environments, often in small cracks and crevices with other algae. Tend to be solitary, but occasionally in small groups. May be encrusted with tunicates and other organisms.