Any ideas?

[Gallma02]

Cream in colour and appears like a balloon with spikes. Was not there a few days ago but appeared now! Any ideas?



Sorry best picture I could get.

 

[nanoreefing4fun]

maybe a harmless Scypha sponge (pineapple sponge)

http://www.melevsreef.com/critters/scypha-sponge

 

[Snid]

Nano's guess is what I was going to say. I had one at one time.

 

[Gallma02]

Thanks both, I will keep an eye on it and let you know of any significant changes

 

[Overlook Reef]

+3 on the pineapple sponge. I have a few in my tank that are just like that.

 

[Oxylebius]

Identification and Husbandry of Aquarium Sponges
http://www.reefkeeping.com/issues/2005-07/rs/

It looks more like the type below then the typical pineapple sponge that is often found as hitchhikers.