Sargasso

Sargasso (サルガッソー Sarugassō) is a planet, albeit in a very loose sense. It is essentially a mass of spider webs, with gigantic spiders to match.

Beast Wars Neo cartoon
When the Gung Ho Maximal crew detected an Angolmois capsule on Sargasso, Big Convoy opted to go alone. There, he was snared by the gigantic spider that lived nearby. Witnessing this capture was Sling and Saberback, who reported back to Magmatron on the Dinosaur. Realizing that Big Convoy's absence provided easy opportunity to hunt down the Angolmois, Magamtron had Guiledart and Dead End teleported to Sargasso to search for the capsule.

With no report from Big Convoy, Longrack attempted to assume command of the Maximals, but they collectively ignored him and went to search for Big Convoy in Sargasso. There, they split into two groups. One group was soon besieged upon by the Predacons, and the other group was wrapped up in the gigantic spider's webs. The two groups met up, and the trapped Longrack attempted to keep ordering around the other Maximals in battle with the Predacons. Fortunately, the competent Big Convoy, who had freed himself from the clutches of the spider, rescued the Maximals and killed the spider in the process. The outnumbered Predacons attempted to escape, but became stuck on the sticky walls of the planet's chambers. Big Convoy put Longrack in his place and had the Angolmois capsule brought to the Gung Ho.

Meanwhile, at the Dinosaur, the ship was infested with tiny spiders that the Predacons had brought aboard.

The AllSpark Almanac
Sargasso was an unclaimed organic planet in the Milky Way.