Sea Squirt
Didemnum vexillum

Tunicate colony of Didemnum sp., with a typical lumpy surface,
encrusting and cementing pebbles and a razor-clam shell that
form the seabed. Northern Georges Bank
(lat 41°51.658' N.,
long 67°25.672' W.); water depth, 58 m; August 2005.
Specimen
is
5.3 in. (13.5 cm) wide; small pebble in lower
center of image
is 0.5 in. (1.2 cm) long. - Dann Blackwood
U.S. Geological Survey
DOI. USGS. Sound Waves Magazine.