In 9000 A.D., the Daleks invaded the planet Phijax III.
While exploring, an advance Dalek squad encountered a colony of Squeeth and their shark-like allies, resulting in a long and brutal battle. Although the Dalek's polycarbide casings made them immune to their paralysing venom, the slightest tentacle flick sent many Daleks crashing into rocks, smashing them to pieces. Others were crushed by the sheer power of the tentacles, squeezing against their outer shells.
The Daleks refused to admit defeat and after days of battle, the Squeeth buckled under the sheer number of Daleks, battle-weary from relentless firepower. After capturing one of the creatures, the Daleks extracted its venom to do tests on. They found that the venom could be used in huge quantities to enslave other worlds by paralysing their inhabitants.
These events were eventually recorded in Daleks: A History by Cornelius Filkins. (PROSE: The Battle for Phijax III [+]Loading...["The Battle for Phijax III (short story)"])