Hyperworm

Hyperworm is a large, purplish annelid with an important role in alien invasion to earthly dimension in X-Com: Apocalypse.

Overview
Hyperworms are voracious worms with just one instinct, and that is to feed as much as it can. They're about the size of a strong man's arm, with one extremity being a large opening with razor sharp and adamantine strong teeth.

This stage of alien lifecycle doesn't produce lethal enzymes that it's predecessor, the Multiworm, does. Or if it does, it no longer has the capability to spit them as projectiles. Instead it fulfills it's short life in a feeding frenzy even more aggressive than that of multiworm's. Their bite can chew through flesh, rock, metal and given time, everything else.

Role in invasion
Hyperworms are used to spread alien presence in Mega-Primus rather than being used as a dedicated fighting force. However, their immense metabolism poses a threat at close range and should not be underestimated. While a single hyperworm is easy to dispatch for any trained soldier, they are often encountered en masse.

If not exterminated soon enough, they will find a sheltered area where their form quickly expands into a fairly large chrysalis. Then, depending on the genetic material the multiworm had been carrying, the chrysalis develops into a fully grown alien creature. Typically they are Anthropods, Skeletoids or Spitters, but can include Poppers  or clusters of Brainsucker  pods.