The King Amoeboid was a large Amoeboid that lived in the sewers on planet Aquatos. Each of them carried a Sewer Crystal which could be collected by defeating it. There were two kinds of King Amoeboids as well. One was found by approaching massive green walls. The other kind could be found in the secret section of the sewers (that could only be accessed with the Gravity Boots) by approaching sewer grates. It was very hard to discern if you had defeated them or not, so you had to check your map if you had the Map-O-Matic to find yourself and to see if there was a Sewer Crystal there. If there was one, you had to use a powerful weapon to attack them. This mutated kind had double attack powers, but half the health of the normal kinds of Amoeboids.
King Amoeboid

In Secret Agent Clank, they appeared in Prison and had a crown on their heads, probably denoting their 'King' status.

A simple way to kill a King Amoeboid was with a shot from the Nitro Eruptor or a charged up blast from the Shock Cannon.

Spiky king amoeboid

Spiky King Amoeboids were an odd variant of the King Amoeboid. The Spiky King Amoeboids only appeared in the upper levels of Aquatos sewers accessed using the Gravity Boots. Despite being more imposing and being encountered later than King Amoeboids, theye were much weaker, as they possessed half the health of a Large Amoeboid. Like King Amoeboids and relinquished a sewer crystal once they were defeated; however, they would drop out of ceiling sections of the sewers instead of appearing from large walls of slime. They are the most silent enemies in the game and their eyes are not glowing.