The Mazon Creek Deposit is known for many enigmatic creatures. Esconichthys is one of them. The animal has a tadpole shaped body with a usually well preserved pair of eyes. Some specimens preserve 2 pairs of long external gills. Muscle segments called myomeres are sometimes present on laterally preserved specimens.  What makes it unusual is that it does not have paired fins. It was originally suggested that Esconichthys may be a larval lungfish or possibly an amphibian