Medical experts in the house, kindly help with this question.
How long can it take an unburied placenta to totally decompose after delivery, if the parents didn't bury or dispose accordingly?

I am aware of a case where the parents just left it in a sealed plastic containers, only for them to find bloody liquid and some small figments after 18 days. Is there a cause for worry?
Kindly help push this to front page for larger audience. Thanks.
Cc: Lalasticlala, Mynd44