Ideas of questionable quality

[RubberRats]

release the mentor moose

[RSOD]

a gene that grows you a second pair of arms at the cost of extra weight and more blood required resulting in a speed penalty and raised stamina cost for sprinting, alongside a lower threshold at which you'll start having bad effects from hypotension

[ju45he]

Some ling limbcritters

Appendix ant that slips you at the cost of its life
Pancreas pirate that steals your pancreas
Liver lender that injects booze
Stomach spider that makes a mess
Heart tart that tastes bad
Mean spleen that can say pre-written insults

[Kotlol]

Appendix ant that slips you at the cost of its life

This is a fun idea for the changeling... not questionable at all!