Mold will look quite "webby" and spread over multiple seeds. Very healthy seedlings will produce root hairs, sometimes called absorbent hairs that are visible to the naked eye and are only found on the root.
If you think you have mold, we have an article that talks more about it here. Since mold spores can be found everywhere, the best way to combat the issue is by controlling moisture.
WAYS TO PREVENT MOLD:
Plant in trays with drainage holes
Air circulation
Avoid planting too densely
Disinfect trays between plantings
Use the bottom watering method
Cut pre-soak time in half
Watering/rinsing less during germination (first 3 days)
Introducing Hydrogen Peroxide or Grapefruit Seed Extract into your watering/soaking regimen: approximately 1 part Hydrogen Peroxide to 8 parts water adjusting ratio as needed for effectiveness.
Switching to a less moisture-retentive medium (soil with added pearlite)
You can find Grapefruit Seed Extract here:
https://www.trueleafmarket.com/products/mold-control?variant=40543778504