1. A freshwater alga (Didymosphenia geminata) that forms thick, slimy mats on stream and river bottoms, often considered an invasive species.
Usage: Also called 'rock snot'; Primarily used in ecological and environmental contexts; Common in New Zealand and parts of North America

Examples

• The river was choked with didymo, making it difficult for fish to spawn.
• Didymo blooms have become a serious problem in several New Zealand waterways.
• Scientists are studying ways to control the spread of didymo in freshwater ecosystems.
• The thick mats of didymo smothered the stream bed and disrupted the local aquatic habitat.
• Anglers have reported that didymo infestations are reducing fish populations in affected rivers.