Identify the resistor type

Can anyone tell me a little about these resistors such as type and characteristics.

Regards, Chris.

OP's photo:

I believe those (R1-R8) are Metal-Oxide Varistors (MOV) intended to suppress large voltage transients coming in on the serial interface lines.

Given the big chip is a quad UART with FIFO, this is likely a modem board and they are almost certainly MOVs to protect from lightning and other voltage spikes as MrMark suggests.

Which indicates this is not your average consumer-grade interface card by any stretch of the imagination.

You would be correct this is from a particle size analyser interface controller used in the labs I wanted to bin the electronics inside because the enclosures are stainless steel.