Seed Shrimp or Freshwater Limpet

[Nic0]

Hi all, I have been noticing little white creatures on the bottom of my 20 gallon aquarium. I have done some research and have narrowed it down to either seed shrimp or freshwater limpets, but I think they are probably seed shrimp. I know they are not bad for the tank, and may even be beneficial, but I am confused in how they got there. I have had the tank running since Christmas time and only have 8 fish in it, 7 serpea tetras and one bristlenose pleco. I do not have any live plants yet, so they could not have hitchhiked on those. I have some wood, but it was very dry when I bought it and I soaked it in water for a day. Could the seed shrimp or limpets have burrowed into the wood and just have come out now. As I said before, I know they are beneficial but they are kind of an eye sore, so is there any way to get rid of them besides sucking them out with a siphon? Is there any type of snail or fish that may eat them? Thanks.