Question Messages log / unknown single digits appearing in list lately

[jam45]

Listed along with the text messages I've received, are these single digits (see screenshot). They are becoming more frequent every day.
I'd like to know what they are, if it's some sort of malware, and how to stop them occurring.
Any advice appreciated. Thank you,

 

[methodman89]

Calls/messages from a spoof number. Just block them. Good luck

 

[mustang7757]

Which Samsung device?
Looking at your screenshot looks to be a group message with that symbol 2 people next to each other , I'll show a screenshot.
I would check each of your contacts under edit on their contact profile to see if any are under that category maybe it was done at one point or work group