From Halopedia, the Halo wiki
The Thanolekgolo specimens present on Alpha Shard exhibited several peculiar qualities in comparison to common Lekgolo. They had a particular sensitivity to active technology due to their ability to detect various forms of disturbances in the air, including magnetic fields, radio waves and electromagnetic pulses, from considerable distances. They could also sense movement, particularly at close range. They were very nimble and fast both by themselves as well as in some of their gestalt forms. The eels were able to jump small distances and exhibited considerable teamwork even in the process of coalescing in and out of their various colony assemblages. They were highly vicious in their behavior and mercilessly devoured any biological organisms and technology they encountered.
List of appearances