I have little white hairs on my live rock

[Myka]

Foraminiferans aka forams? This is a huge group of Protista (not animal nor plant). The ones I am thinking of come in red, pink and white and are spiky and hard. Each color is a different specie I think. They are common and expected in reef aquaria.

Foraminiferans by Ronald L. Shimek "There are similar white foraminiferan species found in aquaria. Their bodies look like small "spiky" versions of a stony coral, rather like nano-sized versions of bird's nest coral, Seriatopora hystrix. These foraminiferans have not been identified to species."