Blue-green algae, also known as cyanobacteria, are tiny organisms found in water bodies like lakes and ponds. Despite their name, they are not true algae but are bacteria that can perform photosynthesis, similar to plants. They often appear as greenish or bluish-green scum on the water's surface, especially in warm, nutrient-rich conditions. These organisms play a crucial role in aquatic ecosystems by producing oxygen and serving as a food source for various aquatic life. However, when they grow excessively, they can create harmful algal blooms that produce toxins, posing risks to both wildlife and human health.