Off topic:print file name having particular extension located in numerous subdirectory

Question

[vmicrobio]

Hello!

I want to print the name of file having '.gbk' extension located in numerous subdirectory within my directory 'test'. However I have an issue with my bash code

#!/bin/bash
files='$.gbk'
if [ "-e home/ha/desktop/test/*/$files" ];
then
echo "$files"
fi

any suggestions?