This is Cryptopleura ruprechtiana (Ruffled Red Seaweed), one of the prettier red seaweeds.
This is Smithora naiadum (Red Fringe), growing on eelgrass.
This Mazzaella splendens (Iridescent Seaweed) is beautiful when it's under water and the sun shines on it.
This seaweed is Odonthalia floccosa (Sea Brush), and it's abundant these days at North Beach.
Here's the beautiful Osmundea spectabilis (Sea laurel, red sea fern).
The red algae, or Rhodophyta (/roʊˈdɒfɨtə/ roh-DOF-fit-tə or /ˌroʊdəˈfaɪtə/ ROH-də-FY-tə; from Ancient Greek: ῥόδον rhodon, "rose" and φυτόν phyton, "plant"), are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species of mostly multicellular, marine algae, including many notable seaweeds. Other references indicate as many as 10,000 species; more detailed counts indicate about 4,000 in about 600 genera (3,738 marine species in 546 genera and 10 orders (plus...