Mystery of the sands

Living in the Outer Hebrides certainly brings variety to life.  Normally our beach is inhabited by ringed plovers, turnstones, hooded crows, seaweed and odd dogwalkers with their charges.  But on Sunday I found what looked like a missile, about half a metre long, labelled 'Danger - Do Not Touch' with what appeared to be spanish or portuguese writing.  Got home and rang the police.  FOUR HOURS (!) later a police team appeared, by which time the object had gone.  Oddly, not washed away by the tide, which was going out at the time.  A mystery - was it picked up by a local, left on the beach as a practical joke, or what?  NEXT DAY, the Coast Guard turned up to investigate.  Just hope whatever it was isn't too dangerous!