Biovore
The Biovore is a Tyranid living artillery. Games Workshop seems to have designed it with the goal of scarring the minds of the 40k fanbase and Neckbeards alike with pseudo-sexual xenos references, as the Biovore model both makes people uncomfortable and generates endless amounts of derp.
With a huge living cannon mounted on their backs, they grow spore mines deep inside themselves and then launch them through a powerful muscle spasm from their mind through their cannon at the enemy. The truth: Biovores reach orgasm in order to fire weird looking spore-seeds from their massive penis guns to assault the enemy, and just to put the icing on the cake these spores explode when reaching the enemy showering them in various nasty liquids. Damn it GW, stop letting Slaanesh write bad xenos slash fiction!
It is no wonder the models look so derpy all the time. Looking utterly clueless and slow it is a wonder if the 'vores could do much in combat if attacked. The fact they are rumoured to have been created using Ork might go a way to explain that; putting two brainless species together is never a smart move... Its newest model is not as derpy. although it does have a ballsack on it's gun so it's really a wash.
On the Tabletop
With the advent of 8th Edition Biovores got really good. Being quite cheap (2 Power/36 points each) their Spore Mine Launchers have been buffed immensely. After you hit a target with a 48" Heavy 1 weapon you roll an additional time: on a 2-6 you deal 1 Mortal Wound, on a 6 you deal D3 Mortal Wounds and on a 1 it fails to do any damage. Mass Biovore fire is now capable of taking down just about anything, hampered only by their BS 4+, their weapon being Heavy and that without Synapse it can only fire at the unit closest to it or suffer a to-hit penalty. The latter can actually be a boon: Missing a lot of biovore shots will allow you to erect a chain of sporemines in front of your opponent's units. And since you are not allowed to move within 1" of your opponent during regular movement, if you leave less than 3" between your mines, your opponent will be unable to move past said wall during his turn! Remember to move your biovores before shooting to gain that extra -1 to hit.