Phylum: Phaeophyta
Class: Phaeophyceae
Order: Chordariales
Family: Ralfsiaceae
Ralfsia pacifica (Hollenberg)

Description: This plant forms a flat encrusting layer, firmly attached to the substrate; it is irregularly circular in outline, often lobed at the margin, 2-12 cm. in diameter, 0.5-1.0 cm. thick, and olive brown to black in colour; surface with radial or concentric rings.

Habitat:  On rocks and shells in the middle and lower intertidal zones.

Pacific Coast Distribution:  Alaska to Mexico.

Robert Scagel, 1972

R. pacifica with several rhodophytes in a tide pool