The unusual type of connective tissue that consists of closely packed cells is blood.

Here's why:

* Connective tissues are typically characterized by cells scattered within a matrix of extracellular material. This matrix can be fibrous, fluid, or gel-like.

* Blood is a fluid connective tissue, but instead of having a solid matrix, its "matrix" is the plasma, a liquid containing dissolved proteins and other substances.

* Blood cells, including red blood cells, white blood cells, and platelets, are suspended within this plasma. They are densely packed, making blood quite different from other connective tissues.

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