Uninvited guest

Just backed from 3-day holiday in Saigon, having seafood,.. and buying some books there.
I hardly find technical books in my field here in Phnom Penh. So, knowing Vietnamese is really an advantage, isn't it?? ;-)

By the way, in front of my house, there is a pond. We easily hear the frog calls after rain. And today as I was about to put my toe in, I felt there was something hidden inside the shoe.

I don't know what it is called in English :p Assuming I'd put my toe in, what it felt like tov nor???