Nautilus processes

Hi I've got a question about Nautilus. Why after starting X there are many Nautilus processes which take a lot of memory. For example: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 11710 turich 15 0 37836 21m 20m S 0.0 2.1 0:02.89 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11711 tu 11710 turich 15 0 37836 21m 20m S 0.0 2.1 0:02.89 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11711 turich 16 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11712 turich 15 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11713 turich 16 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11714 turich 15 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11715 turich 15 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11716 turich 19 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11717 turich 19 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11718 turich 16 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11719 turich 16 0 37836 21m 20m S 0.0 2.1 0:00.04 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11720 turich 15 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11721 turich 20 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 11722 turich 18 0 37836 21m 20m S 0.0 2.1 0:00.00 nautilus --sm-client-id 11c0a80084000111209531400000113030005 --screen 0 1 What for this processes? Are they all necessary? And if no how to kill them?