Wow, a botany question! I am SO THRILLED, even if I'm late to the party.
Like the other folks said, you're stuck with one of the so-called "sea pearls" or "bubble algae", in this case the aforementioned Ventricaria (formerly Valonia) ventricosa. There are many species of "bubble algae", ranging from three species in the genus Valonia that look the most like this stuff, Dictyosphaeria spp. (3 I think) that are more common but possess more "cells", the Halicystis stage of Derbesia osterhoutii (different from the other life history stage which is filamentous), and some folks even like to call certain types of Caulerpa and Microdictyon "bubble algae" too.
Actually from the photo I really can't say for sure if that's Ventricaria you've got there, or the flukey stage of Derbesia. If you're diving deeper than 60 feet, the former is more likely. All of these things anchor with teeny tiny holdfasts; most people assume they just stick to their parent rock or are like tumbleweeds. And many are coenocytic, meaning that the "bubble" is comprised of a single, enormous plant cell containing heaps of cooperative nuclei. Students love hearing about crap like that.
You've also got crustose coralline red algae coating that plant, likely something like Titanoderma pustulatum or Pneophyllum fragile. You'd need a true marine botanist to tell the difference between THOSE things, not just a generic ecologist like me.
I love algae questions so very much.
Like the other folks said, you're stuck with one of the so-called "sea pearls" or "bubble algae", in this case the aforementioned Ventricaria (formerly Valonia) ventricosa. There are many species of "bubble algae", ranging from three species in the genus Valonia that look the most like this stuff, Dictyosphaeria spp. (3 I think) that are more common but possess more "cells", the Halicystis stage of Derbesia osterhoutii (different from the other life history stage which is filamentous), and some folks even like to call certain types of Caulerpa and Microdictyon "bubble algae" too.
Actually from the photo I really can't say for sure if that's Ventricaria you've got there, or the flukey stage of Derbesia. If you're diving deeper than 60 feet, the former is more likely. All of these things anchor with teeny tiny holdfasts; most people assume they just stick to their parent rock or are like tumbleweeds. And many are coenocytic, meaning that the "bubble" is comprised of a single, enormous plant cell containing heaps of cooperative nuclei. Students love hearing about crap like that.
You've also got crustose coralline red algae coating that plant, likely something like Titanoderma pustulatum or Pneophyllum fragile. You'd need a true marine botanist to tell the difference between THOSE things, not just a generic ecologist like me.
I love algae questions so very much.
