Employees at Rolls Royce were surprised to find a turtle wandering around a HGV yard at their Technology and Logistics Centre near Chichester earlier this month.
Staff managed to secure the turtle in a box before putting him into a water-filled sink while they called the RSPCA.
ACO Claire Goddard, who went to collect the Chinese soft shell turtle on the 2nd July, said: "It's a turtle mystery how this little guy got into the warehouse!
"The centre is in the middle of nowhere so I haven't a clue where he's come from.
"Staff spotted him wandering through the warehouse and, unsurprisingly, had quite a shock.
"Luckily, he doesn't seem to be too worse for wear and didn't have any signs of injuries on his head, legs or car-apace (shell).
"He's a lucky turtle!"
It's believed the turtle was abandoned in a pond nearby before making his way onto the industrial estate.
He's been taken to the charity's animal centre for specialist care.