Science tells us that more than 90% of the universe is composed of dark matter and energy. Dark matter is not only found in faraway galaxies but in our own Milky Way. Evidence shows that the Sun and the Solar System are under the gravitational influence of invisible dark matter in our galaxy. Every day and night dark matter particles rain down on Earth. These particles are captured by the Earth's gravitational field. There are therefore many reasons to infer that there are low-density halos of dark matter particles interpenetrating the Earth - effectively creating (currently) invisible 'counterpart-Earths' that co-rotate and share the same gravitational field as the visible Earth. According to Jay Alfred's dark plasma theory, dark matter is composed largely of plasmas of super particles. Dark plasma theory ( Jay Alfred, Our Invisible Bodies, 2006), observes that our visible Earth is gravitationally coupled to counterpart dark matter Earths composed of low density plasma. These "sister Earths" were co-accreted with the physical-dense Earth about 4.6 billion years ago from dark matter components in the embryonic Solar System and supplemented with dark matter carried to Earth by incoming meteors, comets, asteroids and dark matter particles raining down on Earth over the past 4.6 billion years. Plasma life forms evolved on these interpenetrating counterpart Earths, just like it did on the visible planet. These life forms were as varied in scale, structure and intelligence as carbon-based life forms - as different as a microbe from a whale; a mosquito from a tiger; a giraffe from a crocodile; an ant from a human being. Their degrees of intelligence and awareness were as different as a centipede's awareness to the awareness and intelligence of homo sapiens. The taxonomy of these plasma life forms is wide and varied.Some of these plasma life forms have interacted with us in the past (intentionally or unintentionally). The entities that we have loosely identified as ghosts, angels, demons, deities (for example the Marian apparitions in the atmosphere), aliens (associated with UFO sightings in the atmosphere), fairies and sightings of the recently deceased (on the surface of the Earth) are all exotic plasma life forms from interpenetrating counterpart Earths. Homo sapiens evolved carbon-based bodies that formed symbiotic relationships with some of these plasma life forms (indicating a type of symbio-genesis). When the carbon-based bodies died, the bioplasma bodies continued their existence in the counterparth Earths. Dark Plasma Theory is the application of plasma and dark matter physics to the study of plasma life forms and their corresponding habitats. Jay Alfred, an independent and self-funded researcher, has been researching on plasma life forms since 2001. He is a member of ISSSEEM (The International Society for the Study of Subtle Energies and Energy Medicine) and a Consultant at ARPAST (Arkansas Paranormal and Anomalous Studies Team).