Blob
The blob is an amoeba-like green monster whose direction is completely random, and moves only every other turn. The only limits on a blob's direction are illegal moves.
In CC1, the blob is the only monster that is never cloned.
Mechanics
The direction of the blob actually means nothing, even on a clone machine, because the randomly selected direction will take effect from a blob's first move. Because the movement of the blob is not defined in any way, the Controller and Boss Glitch has no effect on it. In Lynx, by contrast, blobs and walkers move in specifically programmed directions.
Acting wall redirecting
There are few strategies for redirecting blobs normally, but sometimes they can be nudged, encouraged, and even forced into a specific path by acting walls, or additionally by existing acting dirt. This can be desirable or undesirable depending on the situation. Usually, if Chip is trying to avoid being hit by blobs in a specific section of route - such as running to the thief in Abandoned Mines - the fewest acting walls are preferred to give the blobs less chance of blocking other blobs' desired directions, such that those blobs would be more likely to hit Chip.
If there is no set route through the room, acting dirt exists in the pathway, or the blobs are instead intended to remove bombs or hit buttons that Chip cannot reach, then blob-acting walls will often help. In the first case, they force the blobs into a more important decision as to which path they are guarding. Acting dirt will also define a safe route through that the blobs cannot infringe on, which is made more secure by the acting walls. The third case is intended to encourage blobs to move closer to the target by reducing its options. If other blobs take away the option of retreating, the initial blob is more likely to move closer to where Chip wants it.
The ultimate situation in blob redirection is the following:
In this case, the blob has only two choices: D back onto a north force floor with no effect, or U, which will send it >U to boot. The same choices then apply, and the second U move leads to death on the bomb, which frees the exit.
Origins
Melinda's special dispatches reveal where the blob came from: it was an accidental creation from a series of failed genetic experiments. Blobnet was the first appearance of the blob, and they largely appeared sparsely from then on. Slo Mo houses 24 blobs out of the 39 that appear in CC1 up until Blobdance, which had to be built when Melinda (admittedly foolishly) tried further experiments.