A lichen is a composite organism consisting of algae or cyanobacteria living symbiotically within the filaments of certain fungi. There are three main types of lichens - foliose, fruticose, and crustose. Lichens allow algae to live in many climates all over the world through photosynthesis, converting carbon dioxide into oxygen that all organisms need to survive.

1. lichens

2. • A lichen is a composite organism that emerges
from algae or cyanobacteria living among the
filaments (hyphae) of two fungi in a mutually
beneficial symbiotic relationship. The fungi
benefit from the carbohydrates produced by
the algae or cyanobacteria via photosynthesis.

3. • There are three main types of
lichens:
• Foliose.
• Fruticose
• Crustose
Three types of lichens

4. Importance of lichens
• Because lichens enable algae to live all over
the world in many different climates, they also
provide a means to convert carbon dioxide in
the atmosphere through photosynthesis into
oxygen, which we all need to survive.