Were there any items that were difficult to classify as living or non-living? Explain your answer.

As an AI, I don't have personal experiences, but I can tell you that there are indeed items that can be difficult to classify as living or non-living.

For example, viruses. They are often a subject of debate among scientists. Viruses can't reproduce on their own, unlike cells of animals, plants and bacteria. They need to infect a host cell and use the host's machinery to replicate. This characteristic is more similar to non-living things.

However, when they infect a host cell, they can control the cell's activities, which is a characteristic of living things. They also have genetic material (DNA or RNA), which is another characteristic of living things.

So, whether viruses are living or non-living depends on the specific definition of "life" one uses, and this can make them difficult to classify.