That's all I can remember; a short story that begins with an astronaut in a landing party dropping a candy or crisp wrapper on the planet's or moon's surface. Unknown to them, there is life on the planet in the form of slime or ooze in a puddle on the ground, that is able to detect available phosphorus - which is low in natural abundance - in the residue on the wrapper. I am pretty sure that it is fairly old - possibly Bradbury?
As mentioned in the comments below, I seem to remember that at the last second, an astronaut picks up the candy wrapper before the party leaves, and ultimately the slime doesn't get the phosphorus after all - an anticlimax from the slime's perspective.
edit: Today's Phys.org article Paucity of phosphorus hints at precarious path for extraterrestrial life reminded me of this question. This gives additional background to the importance of phosphorous in the plot of the short story I'm looking to identify so I've included this excerpt.
Work by Cardiff University astronomers suggests there may be a cosmic lack of a chemical element essential to life. Dr. Jane Greaves and Dr. Phil Cigan will present their results at the European Week of Astronomy and Space Science in Liverpool.
Greaves has been searching for phosphorus in the universe, because of its link to life on Earth. If this element—with the chemical code P—is lacking in other parts of the cosmos, then it could be difficult for extra-terrestrial life to exist.
She explains: "Phosphorus is one of just six chemical elements on which Earth organisms depend, and it is crucial to the compound adenosine triphosphate (ATP), which cells use to store and transfer energy. Astronomers have just started to pay attention to the cosmic origins of phosphorus and found quite a few surprises. In particular, P is created in supernovae—the explosions of massive stars—but the amounts seen so far don't match our computer models. I wondered what the implications were for life on other planets if unpredictable amounts of P are spat out into space and later used in the construction of new planets."
The preliminary results suggest that material blown out into space could vary dramatically in chemical composition. Greaves remarks: "The route to carrying phosphorus into new-born planets looks rather precarious. We already think that only a few phosphorus-bearing minerals that came to the Earth—probably in meteorites—were reactive enough to get involved in making proto-biomolecules.
'If phosphorus is sourced from supernovae, and then travels across space in meteoritic rocks, I'm wondering if a young planet could find itself lacking in reactive phosphorus because of where it was born? That is, it started off near the wrong kind of supernova? In that case, life might really struggle to get started out of phosphorus-poor chemistry, on another world otherwise similar to our own."
The researchers now plan to continue their search, to establish whether other supernova remnants also lack phosphorus, and whether this element, so important for complex life, is rarer than we thought.