I was making a bit of a dash for the door, going to bound up the stairs & about to reach out & grab the railing right where the thing was sitting when I caught a glimpse of it. I'm sure those "puffy-fuzzy" bits on its back are there to cause irritation just like you described.
Funny thing... ...I left the little guy alone instead of crushing 'im with some convenient stick or whatnot, and when I looked for him again after 15 minutes or so of 'Purslane Patrol'**, he was nowhere to be found.
**Ever since a couple of years ago when I discovered a plant called Purslane growing on PCF#0 & let it continue doing so after researching it & finding out it was not only edible, but a good source of omega-3 oils, I've had to be on the lookout for the stuff lest it run goddam wild. It didn't taste repulsive, but it wasn't anything to write home about, either, so I decided I didn't want it around any more.
What it did do, however, was live up to the factoid in its description that stated it could produce thousands of seeds per square foot. Now it pops up everywhere, like an insidious pest, and must be pulled out - roots & all - to be killed. I usually look around for a bit after watering, or when pulling other oddball "space cabbage" - ie, weeds - growing on the Farm just to find it & get rid of it.