allotrope 

one of at least two different forms of an element. Different allotropes of a substance often have very different properties from each other; e.g. white phosphorus (P4) is a highly reactive and toxic substance that glows in air due to its high reactivity and possesses a molecular structure, while red phosphorus (the stuff used to make strikers on match boxes) is a non-toxic substance that has a polymeric structure.

White tin is a shiny, electrically conductive metal usefull for plating cans to prevent corrosion, while gray tin is a semiconductor that possesses no uses whatsoever

allotrope by eszett August 26, 2003

Allotriophagy 

- Noun

The eating of unusual foods, or substances commonly regarded as inedible or innutritious.

{ "Allotrio-" (Gk. "allotrio(s)" Belonging to another) + "-phagy" (L. "-phagus" < Gk. "-phagos" To eat) }

RIP Michel Lotito- Forever to be remembered as "that French guy who ate metal things", and "that bloke who popularised allotriophagy".

Emerson had an inexplicable allotriophagous craving for rotten insect larvae.

Allotriophagy by Charlemagne1993 July 19, 2016

alloprophoric 

"bringing on behalf of others" but implies the selfish twist: the person is bringing something that isn't their own to benefit themselves.
The noun for this would be an allophorist, or the act itself could be called allophory.

You host a BBQ at your house and your brother-in-law makes a ridiculous amount of plates for his friends to come and pick up

"Yo! Stop this alloprophoric behavior at once!"

alloprophoric by fernward September 19, 2025