Bipalium kewense (“hammerhead worms” or Shovel-headed Garden Flatworm or land planarians) are an invasive pest originating in the closed forests of Indo-China / Vietnam
they are 10-20cm long with a hammerhead appearance
they have spread around the world since the 1890s via horticulture in the soil of potted plants
they are also now found in many of the main coastal cities and towns where soils are moist and humid including in Australia (especially around Sydney) but fortunately, rarely seen
some species of Bipalium including this one are toxic by handling them as their secreted mucus contains tetrodotoxin, a neurotoxin which may cause irritation to the skin or mucous membranes
if eaten by cats may cause vomiting
it propagates from sections of its body regenerating into whole worms