I have a barbarian who is using his beast sense to see through his pet Tressym's eyes. The room in question is an icy lodge and has many ice Mephits that are watching but not moving. Do we think he would he be able to see/detect the Mephits with the Tressym's senses?
Ice mephit False Appearance. While the mephit remains motionless, it is indistinguishable from an ordinary shard of ice.
Tressym Detect Invisibility. Within 60 feet of the tressym, magical invisibility fails to conceal anything from the tressym’s sight.
Beast sense: You touch a willing beast. For the duration of the spell, you can use your action to see through the beast’s eyes and hear what it hears, and continue to do so until you use your action to return to your normal senses.