... Supernova showered Earth with radioactive debris . ... Researchers discover that deadly arsenic breathes life into organisms . ... Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. The microorganism substitutes arsenic for phosphorus in its cell components. ... Arsenic, which is chemically similar to phosphorus, is poisonous for most life on Earth. ...