Yellow boring sponge is a common sponge, of which you usually only can see the in- and out-let openings (ostium and osculum). The osculum is a bit higher and larger than the ostium. Because they are close to each other, this is clearly visible. The animal drills itself into calcareous stone or shells. The drilling is done by acid secretion, that dissolves the stone or shell.

The osculum can reach a height of 20 mm and a width of 10 mm. The ostium is flatter and can reach a width of 6mm. Occasionally it can grow to be a massive lump.

Usually yellow, yellow-green or orange.

From the shallow coastal waters, up to a depth of 300 metres.

Almost the entire north Atlantic.