Final answer:
Cyanidiophytes are red algae that are primarily blue-green in color due to their chloroplasts.
Step-by-step explanation:
Cyanidiophytes are red algae that are primarily blue-green in color due to their chloroplasts. They are neither cyanobacteria nor rhodophytes. Cyanidiophytes are known for their ability to thrive in extreme acidic environments, such as hot springs and volcanic areas.
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