"The rough rider of the sea. This bad boy rebel dyed his pincers and his body metallic purple."
Battle Memory

Rock Lobsters are enemies in Mother 3. While they bear a resemblance to the Spineless Lobster found in the passage between Nippolyte's shack and Osohe Castle, the Rock Lobster is stronger and found on the sea floor between Cerulean Beach and Tanetane Island. Their glasses are similar to those of Teddy in EarthBound Beginnings.

Its battle sound is Battle Sound 54 which falls under Code Numbers 921 for regular attack, 922 for Smaaaash! and 923 for Miss.

It is very possible these enemies are a reference to the song "Rock Lobster" by the B52's.