its a temprature probe
on a serious note ive got worms, lol
was doing a ph check today as you do and emptied a jug full of nutrient and there was these little nematodes swimming around in there (not millions only about 3), i did a bit of digging around as ive never seen this before and found that they can either be benificial or destructive depending on what type they are, its not like im gonna have a sample sent of to the local lab to have this shit identified so im gonna take my chances and see what happens, there are way more nematodes that are more helpfull in the root system then there are bad ones, if the plant dies witihn the next 2 weeks then i think we can say they were bad ones lol