Roclobster

Roclobster is a fakemon obtainable in Pokemon Snakewood. It is a Dragon/Rock type and is only obtainable once by using Dive near the dock in Dewford Town. It appears on the overworld as a Rock Smash rock, but when you attempt to break it it attacks, at level 50. It holds the Hard Disk Solo.

Its Pokédex entry states:

B-52's POKéMON

HT/WT   7'03"/176.4 lbs.

We were at the beach Everybody had matching towels Somebody went under a dock

And then they saw a rock But it wasn't a rock It was a ROCK LOBSTER!!

Trivia
Roclobster's name and means of encounter are a reference to the B52s song "Rock Lobster".