Wibbler
This content is a Behavior
Slowly homes in on the player. All Wibblers will, alongside their homing motion, move up-and-down in time with each other, affecting their movement in a predictable manner. This up-and-down is an additive positional effect of a triangle wave, or an additive velocity effect of a square wave, and is not smooth like a sine.
Strategy
These lazy drifters are easy to track and about as easy to avoid. You can even move up and down with them to better shoot them, or move down when they move up (or vice versa) to quickly move out of their threat range.
Notes
It is likely that, among the first-wave accessible enemies, these have the most health. Disregarding how scoring a lot of kills and spawning the most enemies is a good way to accrue EXP, they have the most yield when killed outright via blackholes, grenade pickups, and being extant when the transmission comes in at {5.00*X} Mortality. Add in their relative ease of avoidance, and they may present the best opportunity to eke out more levels early-game.