Space barnacles are a parasitic life-form that attach themselves to spacecraft. Adapting behavior like a computer virus, they drain a host's energy and can only be removed with extreme heat. Space barnacles multiply very quickly, spreading to a new host through physical contact and taking it over in a short amount of time.
They don't normally become shambling horror movie style monsters. Then again, they don't usually cling to vessels that are containing such precious cargo.
Space barnacles attached themselves to the battered and abandoned body of Decepticon leader Megatron, causing Cybertronian energy to be detected by the Autobots, as well as Isaac Sumdac. The space barnacle monster found its way to a mining site, where it dispatched the human overseer through unknown means, and absorbed a pair of digging robots currently working near the entrance.
On an expedition to locate the energy source, Bumblebee, Prowl,and Sari Sumdac set up camp in the forest and were soon attacked by the space barnacle monster. Only after they managed to escape it were they able to identify just what it was, and discovered the mine it had attacked, which was presumed was its lair. Prepared to attack the monster as it exited, the impromptu hunting party was attacked from above, as the space barnacle monster pushed a large pile of snow and debris down on them, trapping Bumblebee and Sari inside the mine. After mistaking a hologram of Prowl for the real thing, the monster rammed the entrance of the mine, removing the debris blocking it and freeing Bumblebee and Sari. The monster chased Prowl into the woods, and was momentarily stunned by the heat from his booster rockets, but was able to overpower him and crushed him against a tree. Just as it was about to deliver the killing blow, the monster was hit by a powerful blast from Bumblebee's stinger guns, sending it tumbling off a cliff and into the shallow river below.
The space barnacles, however, had already infected Prowl, who was now attacking his friends, forcing them to retreat back into the mines to avoid leading the barnacles into the technology-filled streets of Detroit. While in the mines, Sari came up with the plan to destroy the space barnacles with hot water, provided by the heat of the mine's furnace. Before the plan was complete, Bumblebee had become infected, but was subdued by a blast from the fire hose long enough for Sari to get the furnace working and hose both Autobots down with steaming hot water, killing the space barnacles that had infected them.
The body of the space barnacle monster was discovered by Isaac Sumdac, who expressed great interest in what the space barnacles had grown off of...
The state of the space barnacles discovered by Isaac Sumdac is unknown.