[R] Matrix of Matrices?

[Alaios]

Dear all I have a few matrices that I would like to store alltogether under a bigger object.
My matrixes with the same name were calculated inside a loop like

for (few times){

   estimatedsr<- this is my matrix
   savematrixasimagefile();
   

}

which means that I was losing all that instances.
What can I do to keep all these matrices? ( I do not know in advance their number, so I can not preallocate space). 
How can I store them and adress them back again?

I would like to thank you in advance in your help

Best Regards
Alex