About Patelloida alticostata (Angas, 1865)
Patelloida alticostata has a heavy shell, which is narrower toward the anterior end and widest at the posterior third. Its apex sits slightly in front of the shell's center. The shell exterior has 13 to 26 strong axial ribs, with no secondary ribs between them. The shell margin is strongly crenulate. The shell interior is porcellanous white and contains a spatula that may be black, grey, or brown, outlined in black. The shell exterior is usually eroded, but still retains characteristic black cobweb lines between the ribs. Shell length can reach up to 56 mm, while most individuals grow to around 35 mm. This species is endemic to Australia. It occurs from The Entrance in New South Wales to Kalbarri in Western Australia, and is also found in Tasmania. It lives on exposed or moderately exposed rocky shores in the low intertidal and shallow subtidal zones. Around Sydney, this species is more common in subtidal areas than intertidal areas. It prefers bare rock surfaces, as its habitat is limited to small patches of rock.
