Lovecraftian Nightmare
Although it looks like something awful, it’s actually nothing more than a caterpillar. It isn’t anything horrible or terrible; instead, it’s a caterpillar. A Hag Moth caterpillar, to be precise.
It’s a leafy plant, but it has fake arms that are meant to resemble dead leaves and provide camouflage. And hey, it appears to be effective in some manner, as most humans would run away without issue!