The compacted fecal matter which is the
first to pass before the softer normal fecal matter
This can be caused by holding onto the
poo for longer then you should. Cuasing the
colon muscles to compress the fecal matter. Squeezing water and pushing it backwards back up towards the intestine.
Fecal matter after the initial steel head can be more runnier (softer) then usual.
Although it has happened for no reason at all. Its more commonly caused by holding on for to
long or not enough water intake