If someone finds one of your shards, they would need to brute force the remaining 8 seed words left over from a standard 24 word seed. This doesn't sound difficult, but producing these 8 words is enormously labor intensive.
If we assume the attacker had 1 million Nvidia 1080TIs running full time (since there are no ASICs for ECDSA encryption), it would take approx 1.9 million years to guess half of the combinations.
You are quite safe from this scenario.
In fact, the biggest threat of someone finding one of the shards is that you now have no redundancy. You will need every shard you have left if you ever need to recover.
This is why we recommend a yearly check of where you left your shards so if one is missing, you can move the funds and reshard the new seed.