It's the walk cycle. The way it quickly moves its little legs is so cute. It'd probably look more threatening with 6 legs, but what do I know
int dust = Dust.NewDust(projectile.position - projectile.velocity, projectile.width, projectile.height, 229, 0f, 0f, 200, default, 0.8f);
Main.dust[dust].velocity *= -1f;
Main.dust[dust].noGravity = true;