Rhizopus fungus, illustration. Some Rhizopus species are opportunistic agents of humans causing Mucormycosis, a serious fungal infection, usually in people with reduced ability to fight infections. Physicians in India in the first six months of 2021 reported 7200 documented cases of mucormycosis (black fungus) infections in patients with severe COVID-19 infections. In many cases, the patients inhale the mould, which is ubiquitous in soil. After it is inhaled, the mould then travels to the brain. In some more severe cases, the eye or sections of the skull are removed to save the patients. This widespread genus includes at least eight species.