Limaxes are aliens that appeared in Permanent Retirement.
Limax like to eat humans, especially elderly humans, saying children are too chewy and need to age more to become "nice and tender."
Limax are able to shift into any form, including humans, at will. They may alter this form even while retaining a human-like appearance, giving them enhanced flexibility and the ability to stretch their limbs great distances.
They are very strong and capable of lifting and throwing heavy objects with ease. Their speed is such that one was able to keep pace with a golf cart at its maximum speed. Limax are fairly agile and can cling to walls and ceilings with relative ease.
Limax gain strength from heat, as shown when they are attacked by Heatblast. This is the reason they decided to attack a retirement area in the desert (during the summer).
Limax can regenerate and in doing so (sometimes), they create a much larger version of themselves. They can also combine themselves together to make a giant. Here is a picture.
Limaxe are deathly afraid of water. Even just a tiny bit of water may kill them. Although they are vulnerable to water, Limax are able to eat certain animals despite the water they contain, such as houseflies. They also planned to eat humans, which contain a significant amount of water, and no indication was made that they planned to dehydrate them in any way.
Ben 10: Unbound
In a upcoming episode , the Limax will reappear with Ben unlocking a new alien.