Today's interesting fact has to do with the largest and smallest living organism.

The largest one seems to be a fungus, known locally as the "humongous fungus", a honey mushroom. The mycelium of this fungus covers almost 1000 hectares of forest. DNA tests from portions taken throughout the forest has shown that it is all one creature

The smallest one (and note that it self replicates without outside help, in other words, is not a parasite) is a bacterium that is 200 nanometres in diameter. It was found in hot, arsenic filled mine effluent.