These are fungi, specifically, Nidulariales, commonly known as cup fungi or birds nest fungi. The little 'eggs' inside are actually spores, though yours look like they may already have dispersed. The cup fungi themselves are just the fruiting bodies of mycelium within the potting soil. Whilst they will not harm your houseplant, the soil it's sitting in does appear to be overly wet, which will not only encourage this type of fungal growth, but more importantly, may also cause your plant to rot. Hopefully, there is a drainage hole in the pot, and you do not leave any water sitting in an outer tray 30 minutes after watering - assuming that's the situation, you should reduce the amount and frequency of watering. Let it dry out between waterings, so water when the surface of the potting soil feels dry to the touch, water thoroughly, let it drain freely and empty out any excess as described.