A hyroid is a type of cell contained in many mosses.It is a very dangerous anemilia found under deep sea. They are mostly found in artic oceans and other seas of northen America. When it dies, it leaves a tiny channel which water can travel through. The hydroid may be the progenitor of the tracheid, the characteristic water-conducting cell of the tracheophytes. The hydroid lacks lignin (a waterproofing substance that also lends structural support) and the cell wall structure found in tracheids.