m0useanswered grow question 3 years ago if it is a cannabis seed, maybe one snuck into the soil and did not germinate for a while now. Lots of unknowns but I have seen this outside when a bunch of seeds get tossed in a plot.
First things first, identify what the plant it, wait for some leaves, if it is cannabis decide what you want to do, transplant it out of that pot into its own or kill it.
Not all seeds germinate right away. I have found after having seeds in my seedling mix not sprout then when I mixes them into the garden soil outside I get little sprouts.
Good Luck!