This small and vicious bugger is actually a bioweapon. When excited in a certain way, it explodes in a cloud of plague spores, infecting the targets with a deadly disease. It is all the more dangerous, as it ignores all known forms of defense except for natural resistance and sufficiently thick Bottom armor.
The biological nature of this grenade comes with perks: it has a mind of its own, thus increasing base accuracy and reducing no-LoS inaccuracy. It is fast to prime, however, it cannot be unprimed, so be careful when exciting it...