Maelstrom Generators are large generators seen on properties before/while claiming. They generate Stromlings, and continue to do so until smashed.
Once destroyed, they can be rebuilt into an elevator for 6 Imagination to take the player up and retrieve the trapped imagination, rendering the property claimable.
Maelstrom Generators have a health bar like enemies, instead of being smashed on one hit. This health ranges depending on the property. Generators on the Block Yard have 9 health, whereas generators on Avant Grove have around 27.
Maelstrom Generators originated as Maelstrom Shards, meteors sent by the Maelstrom to infect wherever they landed. Like Maelstrom Generators, they spawned Maelstrom enemies: Hyper Darklings, Freak Darklings, and Grumpy Darklings, as well as corrupting whatever was nearby.
The concept of Maelstrom Shards evolved from even earlier ideas, before the concept of the Maelstrom had fully formed. According to concept artist Jerry Meyer, "City scenarios in which some sort of chaotic event would happen caused by some disruptive energy was the first line of thought", and the term Maelstrom and its backstory didn't come along until later. Early concept art/renders of Nexus City show large squid-like things crash landing in the city, which eventually evolved into the idea of Maelstrom Shards.
The Vanguard Outpost, the first truly playable world developed for LEGO Universe, featured a Maelstrom Shard that crashed through the castle's tower/walls and left a crater in the ground.
Maelstrom Shards/Crystals also appeared in early versions of Forbidden Valley. In alpha testing, "Clean the Gardens" achievements could be found in the Forbidden Valley section of the Passport for smashing 25, 75, and 150 Maelstrom Crystals.
Maelstrom Crystals like those found in pre-alpha Forbidden Valley appear in the final game, in The Battle of Nimbus Station, though they simply provide power-ups for the player when smashed.
In the Spider Queen Battle, Dark Spiderlings spawn from grey objects that appear similar to Maelstrom Shards. Oddly, these models were originally created as termite mounds for YouReeka.
A model for a "Darkling Drill" can be found in the game data, which greatly resembles a Maelstrom Generator and is animated to tunnel completely underground.