Shaw's "Squid Baby" may not be her "offspring"

to me the intent is to clearly show that it is the same creature, it isn't in the pod and the the growth may be done in the same way as the xeno grows. the xeno is the size of a fist when it bursts through the chest and then when we next see it its 7ft tall. and the decontamination is for known bacteria/etc, this is an alien entity so it is plausible it may only knock it out temporarily