The Takeover Attempt

Kirk, Spock, and a landing party enter a building in which they find hundreds of small creatures which look like plastic pancakes. The creatures do not register on the tricorder and are highly resistant to phaser fire. When leaving, one of the creature whirls towards them and attaches itself to Spock's back. Back on the Enterprise, McCoy finds that Spock's nerves are being surrounded with strange tissue. Despite his incredible pain (as shown by the K3 indicator), Spock escapes from the sickbay and attempts to take over the bridge before being subdued and tranquillized.