A strand of Worm Grass is oval in shape, with a rounded tip and a bright blue eye-mouth, which opens when alerted, and is used to attach onto and drag prey underground. Its length depends on the position within a patch - generally, the longest strands are in the middle, while shorter ones are closer to the edges. Its color depends on length - short Worm Grass is black, while longer strands tend to take on a deep red.
When alerted, Worm Grass stretch towards potential prey in an attempt to grab it. If successful, they'll limit the creature's mobility, before eventually killing it. Gooieducks can be used to repel both types of Worm Grass, and works best when crawling with one in hand, and not switching directions.
A creature's mass affects resistance to Worm Grass, meaning heavier Slugcats like Hunter and Gourmand are more likely to survive it, while lighter Slugcats like Monk and Spearmaster are particularly vulnerable to it.
Worm Grass can be split into two varieties according to its size and properties:
This variety can be found in small patches in Outskirts, Farm Arrays, Subterranean, and Outer Expanse. While it isn't particularly strong, and the Slugcat can run through it with ease, staying in it for even just a few seconds makes the grip too strong to overcome, leading to death. Black Worm Grass can also be avoided indefinitely by running and jumping to break existing strand attachments.
Exclusive to the large swaths of Worm Grass found in the Farm Arrays (Though if Downpour is installed, red worm grass is present in the DLC exclusive region Outer Expanse), this variety is far stronger and bigger than its black counterpart. Riding a Rain Deer is the safest way of getting across, as any creature that happens to fall into a patch is consumed near instantly. It is possible to break existing attachments, however this method is risky and only works with a few red strands at a time.
Worm Grass hunts by sight and is insensitive to sound and movement. This does not give the player much of an advantage against the grass, but it can be used to detect creatures off-screen. Rain Deer are easily spotted by Worm Grass from far away, and by judging the grass' reaction over time, the player can determine which direction they are walking.
Due to a rendering error, some patches of Worm Grass in the Farm Arrays can appear white.