Mudshark Myth:
The story goes Led Zep was staying in a hotel that overlooked the Seattle Puget Sound for the 1969 Seattle Pop Festival. Bonzo and Zep's tour manager were fishing out of their hotel window into the Puget Sound and they caught a bunch of fish.
Earlier that day Carmin Appice from the band Vanilla Fudge had picked up a groupie and brought her to Bonzo's room. At which point the boys proceeded to pleasure the groupie with the nose of a mudshark.
Now there are many variations of this story (some more salacious than the above version). My opinion is this is not a myth and indeed .....did happen. Now again, there are multiple variations of this story but this probably is not a myth even though the exact details area little convoluted.