Found it on my son's hair after a 10min visit to our veggies garden. My guess is that it might be a tick but we are not in an area of lime disease and although it's an open, rather unkept, field the only mammals I see around are 2-3 stray(?) cats.
The photo was done using a stereoscope+smartphone. The dark lines underneath are .4 to .5 mm.
Any pointers would be welcome.
Also! Might be a bit late now, but I would recommend a thorough search for other ticks on your child. I've found ticks on myself a few times and it's never pleasant, these buggers latch onto your skin and you don't feel them.
You might need a very strong repellant the next time you go into the garden, the DEET ones are effective against ticks. Apply on the neck, waist and shoes as well as on any other exposed skin areas. Stay safe!