so like robot looking things that are actually biological
and have a strong metallic appearance due to the iron
Yea something like that
hmmm okay
any other possible reasons?
That’s all I have really.
alright I guess
yes
reusable substance
drink up
You know you could get your answer 5 times faster if you use this special little thing called an “Internet browser”. It’s free too! 
probably like at least 4 inches
gacha kid
If it’s parasitic
okay I think I have a better reason and that’s tying into @Airconditioner’s idea for them having armor.
and maybe they give some sort of benefit in return so it’s not parasitic
Just cause you need a lot of iron doesn’t mean you shouldn’t eat the body as well
aw man I just wanted them to drink blood
maybe like their bones don’t have a lot of marrow so they need to replace blood from outside sources
Outside sources will evolve to no longer be compatible if they ever were in the first place
What if they only drink the blood because they dehydrate the corpse to eat it later or feed it to their children
well i mean that defeats the purpose of the mutualistic part
maybe we drop the blood idea and try something else I mean if it really doesn’t work 
ohhh ok I missed the mutualistic part. In that case the blood might not evolve to become incompatible