How did unicellular life become multicellular?

     The first step would have been to just band together without forming specialized tissues, as in present-day placozoans.  The second step would have been to start developing some specialized cells, as in the alga Volvox.  Third step: Maybe something like present-day planarians.

    Alternative:  We can just say "I don't see how . . . " and take it from there.  That train of thought leads directly to Goddidit.  End of conversation.

UPDATE:

If askers already know it all, why do they ask?

I don't see how it could go from a  single celled organism whose cells divide, each making a replica of its parent cell, to a multi cellular organism, with differentiated cells, for differentiated cells, which perform different functions within the organism.  Just can't be scientifically.  Evolutionists are all wet on that.  It couldn't happen in a gazillion generations.  If an external action is done on the organism, the organism might undergo a change or mutation, but it would not be passed on in future generations.  That is like when a baby is born with a brain defect due to being deprived of air, it could still produce a child with a normal brain, because it is a one time action.