Flies of the genus Coelopa lay their eggs onto these organisms found decomposing at wrack zones. It’s not diatoms, but non-photochemical quenching in one clade of these organisms is facilitated by allenic pigments called fucoxanthins. The thallus of these organisms comprises the stipe and lamina, which are connected to gas-filled (*) pneumatocysts [new-MAT-uh-sists]. Carrageenans synthesized by (10[1])these organisms are harvested for use as food thickeners. Eel migration is speculated to be propagated by (-5[1])free-floating kinds of these (-5[1])organisms named after the Sargasso Sea. Sea otters are a keystone species of these organisms’ namesake ecosystems. For 10 points, name these plant-like algal organisms that form (10[1])namesake underwater (10[1])“forests.” (10[1])■END■