Can microorganisms be seen with the naked eye?

Most microorganisms cannot be seen with the naked eye because they are extremely small and require a microscope for observation. Bacteria, protozoa, and viruses are measured in micrometers or nanometers, making them invisible without magnification.

However, a few microorganisms can sometimes be seen without a microscope. For example, fungi like moulds on bread and mushrooms are visible to the naked eye. Large colonies of bacteria or algae may also appear as patches or layers, but the individual organisms are still microscopic.

Microorganisms are generally too small to be seen with the naked eye, but some fungi and algal colonies can be visible when they grow in large numbers.