Sea Spiders
They differ from their land counterparts in a number of ways. They do not spin webs underwater and may have up to 6 pairs of long segmented legs that generally end in small claws. They also possess 2 or 4 pairs of eyes but totally lack any excretory or respiratory organs will all waste product being released and oxygen taken up by crossing cell walls.
Like land spiders, sea spiders are carnivorous, feeding on other invertebrates by sucking out their juices through a proboscis inserted into prey. Common prey include anemones, hydroids, bryozoans or even nudibranchs.
They are generally very small at less than 10mm and lack movement so they don't tend to attract attention to themselves and hence not easily spotted by divers. The sea spiders pictured were at the Pinnacle and the habitat photo shows three spiders clustered together where they were found. The same species has also been spotted recently at Sunset and Avoca Pinnacle so keep a close eye out for these little guys on your next dive.