Green mould

Penicillium is genus of moulds found everywhere world-wide.
The name Penicillium comes from the resemblance of the spore producing structures (conidiophores) of the fungus to a paintbrush (penicillus is the Latin word for paintbrush). They are found in soil, decaying vegetation, air and are common contaminants on various substances.
Penicillium causes food spoilage, colonizes leather objects and is an indicator organism for dampness indoors. Some species are known to produce toxic compounds (mycotoxins). The spores can trigger allergic reactions in individuals sensitive to mould. Therefore, the health of occupants may be adversely affected in an environment that has an amplification of  Penicillium.