In answer to your question, my understanding is that they will not eat them but I could be wrong. For the most part, they stay buried in the sand. To the best of my knowledge, they will have no bearing on your plant growth. The main purpose they serve is to keep the sand loose and non-compacted. The plant roots will do tht on ttheir own. I just want to relay my personal experience with MTS. I had a few and then a few more and then a few more until I was absolutely over run. They took over my tank. I could dip up a table spoon of sand and there would literally be a hundred in it. I finally had to break the tank down and completely change the substrate to get rid of them. If you get them, make sure you don't overfeed. They will feed on the excess food and in no time at all, as mentioned, you willl have a snail population explosion. I will never voluntarily have them in my tanks again