Do not add alternative names or other options to this crowner.
Understanding the name requires familiarity with the original metal slime enemy, since "metal [noun]", "[adjective] slime", and "metal slime" do not evoke the trope, though they do evoke one of the possible variants of one of the required traits.
Listing a monster type on a works page as a Metal Slime is counterintuitive for people who don't know the trope, since the name better fits an otherwise weak monster with very high defense—a common trait of Metal Slimes, but hardly necessary and certainly not the most important part of the trope.
Alternative names have been offered that are concise and considered descriptive and accurate by some. No rename will occur until consensus has been reached on an alternative.
Tropes are not only of interest to particular fandoms and all other site guidelines trend to not make assumptions of reader involvement in fandoms.
Assumptions as to the knowledge of genre fans, without any actual proof, remains subject to Fan Myopia.