In case you skip it...

Remember Admiral Quinn and Commander Remmick?

They came aboard the Enterprise in “Coming of Age”, investigating a possible conspiracy to destroy the Federation. Well, it turns out the threat was real - it’s a race of neural parasites. They’re a few inches long and they look like this:

They enter a humanoid host and attach themselves to the brainstem, taking control of the host body. Several high-ranking members of Starfleet Command had apparently been compromised. In the time since their last appearance, Remmick and Quinn were taken over as well.

They aren’t very subtle, though, and the Enterprise crew figures out what’s going on pretty quickly. It turns out that Remmick is host to the ‘mother’ creature, and once they blow him up the other creatures die and their hosts apparently make a full recovery.

AAAAAAAH AAAAAAAH SO WEIRD AND GROSSS AAAAAAAAH

WHY IS THAT IN STAR TREK AAAAAAAAH