Panspermia Theory suggests that life seeds came from outer space and planets exchanged life. Panspermia literally means seeds everywhere.

Terence McKenna on Interstellar Mushroom Spores

What the mushroom says about itself is this: that it is an extraterrestrial organism, that spores can survive the conditions of interstellar space. They are deep, deep purple — the color that they would have to be to absorb the deep ultraviolet end of the spectrum. The casing of a spore is one of the hardest organic substances known. The electron density approaches that of a metal.

Is it possible that these mushrooms never  evolved on earth? That is what the Stropharia cubensis itself suggests. Global currents may form on the outside of the spore. The spores are very light and by Brownian motion are capable of percolation to the edge if the planet’s atmosphere. Then, through interaction with energetic particles, some small number could actually escape into space. Understand that this is an evolutionary strategy where only one in many billions of spores actually makes the transition between the stars — a biological strategy for radiating throughout the galaxy without a technology. Of course this happens over very long periods of time. But if you think that the galaxy is roughly 100,000 light-years from edge to edge, if something were moving only one one-hundredth the speed of  light — now that’s not a tremendous speed that presents problems to any advanced technology — it could cross the galaxy in one hundred million years. There’s life on this planet 1.8 billion years old; that’s eighteen times longer than one hundred million years. So, looking at the galaxy on those time scales, one sees that the percolation of spores between the stars is a perfectly viable strategy for biology. It might take millions of years, but it’s the same principle by which plants migrate into a desert or across an ocean.

I don’t necessarily believe what the mushroom tells me; rather we have a dialog. It is a very strange person and has many bizarre opinions. I entertain it the way I would any eccentric friend. I say, “Well, so that’s what you think.” When the mushroom began saying it was an extraterrestrial, I felt that I was placed in the dilemma of a child who wishes to destroy a radio to see if there are little people inside. I couldn’t figure out whether the mushroom is the  alien or the mushroom is some kind of technological artifact allowing me to hear the alien when the alien is actually light-years aways, using some kind of  Bell nonlocality principle to communicate.

The mushroom states its own position very clearly. It says, “I require the nervous system of a mammal. Do you have one handy?”

– Terence McKenna – Tryptamine  Hallucinogens And Consciousness