While they can be rather shocking at first, they are not that uncommon in our Texas Blackland Prairie region.Diplocardia fusca is one locally identified species, which this may be? We usually see them come out at night after good rains as their habitat area gets flooded. Nothing to be alarmed about. hope this helps, if I or we can be of any further service call or come by our office at 701 S. I-35 E, Waxahachie, Texas or call<personal data hidden>. Mark Arnold CEA-Ag.