Those are called, "Platelets".
A tangled mesh of blood cells is called a blood clot.
Blood clotting involves platelets.
Platelets
stationary clot is called a thrombus or a blood clot.
Platelet cells are the component within blood cells that help control bleeding by helping blood to clot.
White blood cells help clot the blood. Low PH makes red blood cells clump together
platelets
Blood clot
You need to be more descriptive with your question. There are lots of things that could be called "clot tubes". Small blood vessels are called capillaries. The blood cells that play a primary role in clotting are called platelets.
the part of the blood that closes a wound is called the platelets.
red blood cells
A fixed blood clot is called an embolus.