Tasmanian devil with a tumour
A tumour (or tumor) is tissue that is growing where it should not be. Another name for a tumor is neoplasm. Tumours are either malignant (harmful) or benign (safe). Cancer, for example is malignant and sometimes spreads to other places on the body. Some tumours have a cause that makes them grow. For some tumours no cause is known. A tumour usually forms as a lump or mass.
The Tasmanian Devils in Tasmania, Australia are in danger of becoming extinct because of a malignant tumour that grows on their face.