It seems the compost I used was more lively than anticipated. There's an earthworm crawling around in there.
It's a decent 12 inch pot, but it's still effectively a limited environment. So I'm not sure if I should leave him in or take him out.
UPDATE: alright. I'll keep him in, cross my fingers, and hope I've pulled in enough of an ecosystem to both sustain him for his expected lifespan, and safely handle the subsequent death and decomposition.
Leave to where, though? Personally I would relocate the worm to the outdoor garden where I have seen plenty of worm friends rather than risk a pet hurting him when he decides to relocate. If the potted plant was being kept outdoors I would leave the worm in.
It's an indoor plant, so I guess finding it's way out of the apartment would be the challenge.
It's an indoors office plant. If it ends up leaving the pot, it'll likely end up getting rolled over by some chair wheels.
Given the soil mix I used, it'll likely be very happy for the rest of its life.