In late May 2018, I came across this planarian among the leaves on the forest floor in Cuyahoga County, Ohio. Planarians are part of the group of animals known as Platyhelmintes. Although planarians look a bit like earthworms, they are only distantly related to earthworms and other members of the Annelida. Interestingly, there are many planarians that hunt and eat earthworms.
Although, I knew it was a planarian, I did not know that they could be found in Ohio. Some investigation on my own, and helpful information from contributors on iNaturalist indicated that this was probably a Wandering Broadhead Planarian (Bipalium adventitium). These are an introduced species here in Ohio. If you come across them in Ohio or other parts of the midwest, I would be interested in hearing about it and seeing photos. Please feel free to contact me at mfbenard (at) gmail.com