sea wedge

My heart is filled with sadness: my Dolabella/Wedge Sea Hare's back has split open and his shell is sticking out. It happened overnight. My parameters are: 1.024 salinity .5ppm Nitrates 0/0 Ammonia/Nitrites I bought him two weeks ago to clear out a ton of green hair algae, there is plenty...

Hi all, I need help with this one. I've had this sea Wedge hare for about 6 months and all of a sudden, two days ago, this weird blue thing came out of the side of its head! Almost like out of its mouth! I don't know what this is but it is prohibiting him from eating. I think it's gonna die...