Family Description:
Members of this family come in a wide variety of forms, from cylindrical and branched to flattened blades. Some species have a single axial filament, whereas others have a multiaxial filamentous medulla. What unites these species into a single family is the occurrence of the carpogonium at the end of branch of beadlike cells and similarities in the formation of carposporangia after the carpogonium has been fertilized. All of the species described here have an alternation of isomorphic generations, and male and female reproductive structures usually occur on separate individuals.
Species in this family have unusual cell wall carbohydrates that have been shown to have antiviral properties.

Species description:
Another species, Cracked Saucer, is present throughout most of our area. It develops new blades at the end of the stipe which protrudes through last year's blades. The stipe begins to protrude in May or June. Hence in the late spring and summer of any year you will see the current year's blade with an elongated nipple projecting above its center. In addition to its protruding stipe, Cracked Saucer can also be distinguished from Cup and Saucer by the larger mature size of its blade (up to 30 cm or more—12+ in) in diameter, which tends to tear radially into floppy, wedge-shaped sections. Also, you can easily see veins in the blade, especially on the under side.

Individuals collected from southern British Columbia/northern Washington State were able to withstand a week of immersion in water at a temperature of 23°C (74°F) but died when placed in warmer water.

Source:  North Pacific Seaweeds