Archa Seven Arachnid

Aracha Seven Arachnids are an unnamed race of nasty and terrifying spider-like aliens that from the planet Archa Seven.

History
A thousand stellar cycles ago or so, Autobots Optimus, Sentinel, and Elita-1 arrived on Archa Seven due to rumors of the Decepticon starship Twilight having crash-landed there. Optimus objected to the mission because organic planets were off-limits to Autobots. However, Sentinel emphasized that the Decepticons were chronic hoarders of Energon and that if they found the Twilight, they were bound to be set for life.

After accidentally falling into the planet's underground cavern network, the three Autobots were attacked by the native arachnids and separated from each other. When Optimus eventually found the wreckage of the Twilight, he discovered that the ship had been turned into a nest for the spiders. In their attempt to escape, Optimus and Elita detonated the energon stockpile in hopes of killing the spiders. However, Elita was left behind to fend off the spiders on her own.

When she was bitten, Elita used her "download" ability on their venom only to transform into a techno-organic hybrid creature dubbed "Blackarachnia". Additionally, Blackarachnia's alternate mode became a techno-organic version of the Archa Seven arachnid. Because of her new nature, her energy signature was no longer present on Optimus's radar, leading him and Sentinel to believe that she had perished in the explosion.