Possible Clues:

• Sea drifters?
• It sound as if Algernon is both green and primitive
• Bloom makeup
• Simple plants produced liquor - over a gallon drunk?
• To be in the water might make Algernon sound green
• Biofuel source
• Aquatic flora
• Simple aquatic organisms
• Slimy aquarium growth
• Pond scum and kelp