Somehow, Rocky actually wins the snail race despite not showing any signs of sentience. Squidward himself was confused by how his pet snail lost to a rock.
"The Endless Summer"
When Patrick says to Mr. Krabs that he and the people of Bikini Bottom are moving to colder climates, he is holding a stick with Rocky strapped with a rope to the end of the stick. Rocky is lumpy and gray in this short.
"Buried in Time"
Patrick wants to donate Rocky to the time capsule. In this episode, however, Rocky is lumpy and gray, possibly meaning that he somehow got older.
When SpongeBob says "Ooh, a shadow puppet show," Patrick says "SpongeBob, please," while holding Rocky.
Meow...Like a Snail?!
He is seen in the "The Great Snail Race" segment of the book.
In "The Great Snail Race," Rocky does not move, but at the end, he is last seen on the finish line.
It is possible the Mayor put Rocky at the finish line so that the race would have a winner.
Rocky could have won by Patrick helping him along the track without stepping on the track himself, but that begs the question of why Patrick wasn't disqualified for setting foot on the track.
According to Patrick, Rocky has nerves of steel. Whenever someone mentions to Patrick that his pet is an actual rock, with Patrick continually mentions this, saying, "I know, I know, he's got nerves of steel."
In “The Great Snail Race,” Rocky has a similar appearance to Patrick’s house.