Cats, nightmares, and calcium deficiency

I recently had a nightmare about my (2) cats having really brittle bones, in which a couple of their feet snapped off and their wings(?!) broke halfway on each

I woke up and took this as a sign that my cats aren't getting enough calcium, which led me to Googling "how cats get calcium" in an attempt to find out if I'm doing it wrong
This was at 1:45am

So what I'm trying to ask is; "How do cats get their calcium?"