Dirt - Internally Colonised

Return to Earth has been halted awakened from our sleep primary mission has changed,
Respond to unknown transmission
how were we to know?

Through these unearthly halls, we've wandered into the alien nest.
best to leave them well alone or they'll break straight through your chest!

Impregnated by an alien parasite to colonize from within.
Bursting forth from the rib-cage to birth this ungodly creature,
spawned from hell with desires of evil
it will kill us all.
Shedding its skin, it has grown again,
you've doomed us all!