I checked my car engine bay thoroughly. I have seen that left hose which is fitted with car body is connected to right hose by connecting single hose pipes which is also fitted to car body.
And at engine side, hose which is for heater near the thermostat is connected to hose near the distributor by same single pipe. Just they changed the position of pipes. This can be re-fitted to original fitting at home.
No-one insert something in hoses.
Now after seen this condition, I am now satisfied that there is no more harmful thing for my car.