I think so, but there are MANY kinds of flatworms. This has been in a tank with only ricordea, Duncan, and fathead dendro for weeks, so we can rule out the kind that feed on SPS.
I have a ton of the beige brown kinds. The multiply really fast once they settle in and they can grow really big. They do a good job of cleaning the glass under the sand bed, so definitely a nice hitchhiker to have.