Random large coloured emojis appearing in Thunderbird email list

Question

Since I upgraded from Ubuntu 17.10 to Ubuntu 18.04 whenever I open Thunderbird there is a globe icon, and sometimes also headphones icon, appearing in my list of new emails.

These icons hide the titles of my emails. When I move the mouse over the icons they partially disappear. When I scroll down there is another globe icon further down the list.

Answer 1

Installing the fonts-symbola package fixes the problem.

sudo apt-get install fonts-symbola