Weird Plants Growing from Indoor Tomato pots?

[Chicken-Eye]

I recently started planting tomato plants indoors and once they sprouted, I noticed weird weedlike plants growing from the same pot. The seedlings will obviously get moved when they get bigger, but what about the weird weed plants? What should I do with them?

(The plant is circled in red)

 

[CascadiaRiver]

It could be just about anything!

 

[Chris09]

Pull the weed out, there was weed seeds in the soil that you used.
If you don't want to get weeds in your seed starting pots you need to use a good soilless mix that has been sterilized.

 

[harmesonfarm]

looks like a weed snuck in! i have those happen in my seeding mixes once in a while, particularly if it was an open bag that i used the next spring...their sneaky buggers!

 

[Chicken-Eye]

Alright, thank you. This was a black soil, potting aoil and wild soil mix.