Which protist is multicellular, found in warm ocean waters and has a red color due to the red photosynthetic pigments in its cells?

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).

this is a good question! i'll do some research and come back when i have the answer!